CN113228490A - Drive control device, drive device, and power steering device - Google Patents

Abstract

One embodiment of the drive control device is a drive control device that controls driving of a motor, and includes: a first inverter connected to one end of a winding of the motor; a second inverter connected to the other end opposite to the one end; a first control circuit that performs PWM control of the first inverter; a second control circuit that performs PWM control of the second inverter; and a common clock that supplies a clock signal for PWM control to both the first control circuit and the second control circuit.

Description

Drive control device, drive device, and power steering device

Technical Field

The invention relates to a drive control device, a drive device, and a power steering device.

Background

Conventionally, a cordless motor having n-phase windings (coils) and having no wires connecting the coils to each other is known. As a method of driving such a cordless motor, a so-called full-bridge driving system is known in which an inverter is connected to both ends of a coil of each phase. In the driving of the full-bridge cordless motor, two inverters are normally driven, and one inverter is switched to a neutral point to perform three-phase control in an abnormal state. In addition, from the viewpoint of reducing the failure rate, a configuration is known in which two inverters are controlled by two control circuits. For example, in patent document 1, a first control unit controls driving of a first inverter, and a second control unit controls driving of a second inverter.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-

Disclosure of Invention

Technical problem to be solved by the invention

From the viewpoint of reducing the failure rate, it is preferable that there is no independent driving of circuit portions which are common to the control circuits. However, in the case of the full-bridge drive system, if a synchronization shift occurs in the PMW carrier signal of each control circuit, the torque ripple of the motor deteriorates. As the synchronization of the carrier signal, frequency synchronization and phase synchronization can be considered, and if the frequency synchronization is deviated, the deterioration of the torque ripple is significant. Although the degree of synchronization deviation is lower than that of frequency, torque ripple is deteriorated even if the phase is synchronized. Therefore, an object of the present invention is to reduce torque ripple while ensuring independence of control circuits.

Technical scheme for solving technical problem

One aspect of the drive control device according to the present invention is a drive control device that controls driving of a motor, including: a first inverter connected to one end of a winding of the motor; a second inverter connected to the other end opposite to the one end; a first control circuit that performs PWM control of the first inverter; a second control circuit that performs PWM control of the second inverter; and a common clock that supplies a clock signal for PWM control to both the first control circuit and the second control circuit. In addition, one embodiment of the driving device of the present invention includes the drive control device and a motor controlled to be driven by the drive control device.

In addition, one embodiment of the power steering apparatus of the present invention includes: the drive control device described above; a motor driven by the drive control device; and a power steering mechanism driven by the motor.

Effects of the invention

According to the present invention, torque ripple can be reduced while ensuring independence of the control circuits.

Drawings

Fig. 1 is a diagram schematically showing a block configuration of a motor drive unit of the present embodiment.

Fig. 2 is a diagram schematically showing a circuit configuration of the motor drive unit of the present embodiment.

Fig. 3 is a diagram showing the values of currents flowing through the coils of the respective phases of the motor.

Fig. 4 is a diagram schematically showing a state of voltage application in the switching operation under the PWM control.

Fig. 5 is a diagram schematically showing a state where application is stopped in the switching operation under the PWM control.

Fig. 6 is a diagram showing the PWM signal.

Fig. 7 is a diagram schematically showing the hardware structure of the motor drive unit.

Fig. 8 is a diagram schematically showing the software configuration of the control circuit.

Fig. 9 is a diagram showing a circuit configuration of a motor drive unit in a modification in which circuit wirings are different.

Fig. 10 is a diagram schematically showing the configuration of an electric power steering apparatus according to the present embodiment.

Detailed Description

Hereinafter, embodiments of the drive control device, the drive device, and the power steering device according to the present disclosure will be described in detail with reference to the drawings. However, in order to avoid unnecessarily long descriptions below, it is easy for those skilled in the art to understand that the detailed descriptions above may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of substantially the same structures may be omitted.

In the present specification, an embodiment of the present disclosure will be described by taking as an example a drive control device that supplies power from a power supply to a three-phase motor having three-phase (U-phase, V-phase, W-phase) windings (sometimes referred to as "coils"). However, a drive control device that supplies electric power from a power supply to an n-phase motor having four-phase or five-phase (n is an integer of 4 or more) windings is also within the scope of the present invention.

(Structure of Motor drive Unit 1000)

Fig. 1 is a diagram schematically showing a block configuration of a motor drive unit 1000 of the present embodiment. The motor drive unit 1000 includes inverters 101 and 102, a motor 200, control circuits 301 and 302, and an external clock 450.

In this specification, a motor drive unit 1000 having a motor 200 as a component will be described. The motor drive unit 1000 having the motor 200 corresponds to an example of the drive device of the present invention. However, the motor drive unit 1000 may be a device for driving the motor 200, the motor 200 of which component is omitted. The motor drive unit 1000 in which the motor 200 is omitted corresponds to an example of the drive control device of the present invention.

The motor drive unit 1000 converts electric power from the power source (403, 404 of fig. 2) into electric power to be supplied to the motor 200 through the two inverters 101, 102. The inverters 101 and 102 can convert dc power into three-phase ac power, which is a pseudo sine wave of U-phase, V-phase, and W-phase, for example. The two inverters 101, 102 include current sensors 401, 402, respectively.

The motor 200 is, for example, a three-phase ac motor. The motor 200 has coils of U-phase, V-phase, and W-phase. The winding manner of the coil is, for example, concentrated winding or distributed winding.

The first inverter 101 is connected to one end 210 of the coil of the motor 200, and applies a driving voltage to the one end 210, and the second inverter 102 is connected to the other end 220 of the coil of the motor 200, and applies a driving voltage to the other end 220. In this specification, "connection" of components (constituent elements) means electrical connection unless otherwise specified.

The control circuits 301, 302 include microcontrollers 341, 342, etc., which will be described in detail later. The control circuits 301, 302 control the drive voltages of the inverters 101, 102 based on input signals from the current sensors 401, 402 and the angle sensors 321, 322. As a control method of the inverters 101 and 102 by the control circuits 301 and 302, for example, a control method selected from vector control and Direct Torque Control (DTC) is used.

The external clock 450 provides a common clock signal to both control circuits 301, 302, such that the control of the inverters 101, 102 in both control circuits 301, 302 is synchronized primarily in frequency. A specific circuit configuration of the motor drive unit 1000 will be described with reference to fig. 2. Fig. 2 is a diagram schematically showing a circuit configuration of the motor drive unit 1000 of the present embodiment.

The motor drive unit 1000 is connected to the independent first power supply 403 and second power supply 404, respectively. The power supplies 403 and 404 generate a predetermined power supply voltage (for example, 12V). As the power sources 403 and 404, for example, a dc power source is used. However, the power sources 403 and 404 may be AC-DC converters or DC-DC converters, or may be batteries (secondary batteries). In fig. 2, a first power supply 403 for the first inverter 101 and a second power supply 404 for the second inverter 102 are shown as an example, but the motor drive unit 1000 may be connected to a single power supply common to the first inverter 101 and the second inverter 102. The motor drive unit 1000 may include a power supply therein.

The motor drive unit 1000 includes a first system corresponding to the one end 210 side of the motor 200 and a second system corresponding to the other end 220 side of the motor 200. The first system includes a first inverter 101 and a first control circuit 301. The second system includes a second inverter 102 and a second control circuit 302. The inverter 101 and the control circuit 301 of the first system are supplied with power from the first power source 403. The inverter 102 and the control circuit 302 of the second system are powered by a second power source 404.

The first inverter 101 includes a bridge circuit having three branches. Each branch of the first inverter 101 includes a high-side switching device connected between the power supply and the motor 200 and a low-side switching device connected between the motor 200 and the ground. Specifically, the U-phase arm includes a high-side switching device 113H and a low-side switching device 113L. The V-phase arm includes a high-side switching device 114H and a low-side switching device 114L. The W-phase arm includes a high-side switching device 115H and a low-side switching device 115L. As the switching element, for example, a field effect transistor (MOSFET or the like) or an insulated gate bipolar transistor (IGBT or the like) is used. In addition, when the switching element is an IGBT, a diode (free wheel) is connected in anti-parallel with the switching element.

The first inverter 101 is provided with shunt resistors 113R, 114R, and 115R in each branch as, for example, a current sensor 401 (see fig. 1) for detecting a current flowing through each phase winding of the U-phase, the V-phase, and the W-phase. The current sensor 401 includes a current detection circuit (not shown) that detects a current flowing through each shunt resistor. For example, a shunt resistor may be connected between the low- side switching elements 113L, 114L, and 115L and the ground. The shunt resistor has a resistance value of, for example, about 0.5m Ω to 1.0m Ω.

The number of shunt resistors may be other than three. For example, two shunt resistors 113R and 114R, V for the U-phase and V-phase, two shunt resistors 114R and 115R for the W-phase, or two shunt resistors 113R and 115R for the U-phase and W-phase may be used. The number of shunt resistors to be used and the arrangement of the shunt resistors may be determined appropriately in consideration of product cost, design specifications, and the like.

The second inverter 102 includes a bridge circuit having three branches. Each branch of the second inverter 102 includes a high-side switching device connected between the power supply and the motor 200 and a low-side switching device connected between the motor 200 and the ground. Specifically, the U-phase arm includes a high-side switching device 116H and a low-side switching device 116L. The V-phase arm includes a high-side switching device 117H and a low-side switching device 117L. The W-phase arm includes a high-side switching device 118H and a low-side switching device 118L. The second inverter 102 includes, for example, shunt resistors 116R, 117R, and 118R, as in the first inverter 101.

The motor drive unit 1000 includes capacitors 105, 106. The capacitors 105 and 106 are so-called smoothing capacitors, and absorb a circulating current generated by the motor 200 to stabilize a power supply voltage and suppress torque ripple. The capacitors 105 and 106 are, for example, electrolytic capacitors, and the capacity and the number of capacitors to be used are appropriately determined in accordance with design specifications and the like.

Reference is again made to fig. 1. The control circuits 301 and 302 include, for example, power supply circuits 311 and 312, angle sensors 321 and 322, input circuits 331 and 332, microcontrollers 341 and 342, drive circuits 351 and 352, and ROMs 361 and 362. The control circuits 301, 302 are connected to the inverters 101, 102. The first control circuit 301 controls the first inverter 101, and the second control circuit 302 controls the second inverter 102.

The control circuits 301 and 302 can control the position (rotation angle), rotation speed, current, and the like of the target rotor to realize closed-loop control. The rotation speed is obtained by time-differentiating the rotation angle (rad), for example, and is indicated by the rotation speed (rpm) at which the rotor rotates in a unit time (e.g., 1 minute). The control circuits 301 and 302 can also control the target motor torque. The control circuits 301 and 302 may be provided with torque sensors for torque control, but torque control is possible even if the torque sensors are omitted. Further, a sensorless algorithm may be provided instead of the angle sensors 321 and 322. The power supply circuits 311 and 312 generate DC voltages (e.g., 3V and 5V) necessary for the respective blocks in the control circuits 301 and 302.

The angle sensors 321, 322 are, for example, resolvers or hall ICs. The angle sensors 321, 322 may also be realized by a combination of a Magnetoresistive (MR) sensor having an MR element and a sensor magnet. The angle sensors 321, 322 detect the rotation angle of the rotor of the motor 200, and output rotation signals showing the detected rotation angle to the microcontrollers 341, 342. Depending on the motor control method (e.g., sensorless control), the angle sensors 321 and 322 may be omitted.

The input circuits 331 and 332 receive motor current values (hereinafter referred to as "actual current values") detected by the current sensors 401 and 402. The input circuits 331 and 332 convert the level of the actual current value into the input level of the microcontrollers 341 and 342 as needed, and output the actual current value to the microcontrollers 341 and 342. The input circuits 331 and 332 are analog-digital conversion circuits.

The microcontrollers 341, 342 receive the rotation signals of the rotors detected by the angle sensors 321, 322, and receive the actual current values output from the input circuits 331, 332. The microcontrollers 341 and 342 set a target current value based on the actual current value and the rotor rotation signal, generate PWM signals, and output the generated PWM signals to the drive circuits 351 and 352. For example, the microcontrollers 341 and 342 generate PWM signals for controlling the switching operation (on or off) of the switching elements in the inverters 101 and 102.

The generation of the PWM signal in each microcontroller 341, 342 is performed in synchronization with the frequency of the clock signal supplied from the common external clock 450, respectively. That is, the external clock 450 is an example of a common clock that supplies a clock signal for PWM control to both the first control circuit 301 and the second control circuit 302. Since the clock signals obtained from the external clock 450 have the same frequency between the control circuits 301 and 302, the PWM control frequencies in the two control circuits 301 and 302 are synchronized with each other, which ensures independence, and torque ripple can be reduced.

The clock signal from the external clock 450 is monitored by a monitoring function, such as a fail-safe clock monitor, provided in each of the microcontrollers 341, 342. Each microcontroller 341, 342 has an internal clock 371, 372. When the clock signal from the external clock 450 fails, the monitoring function detects the failure, and the operation of each of the microcontrollers 341, 342 is switched to the operation according to the clock signal from the internal clocks 371, 372. As a result, the microcontrollers 341 and 342 continue to generate PWM signals in accordance with the clock signals from the internal clocks 371 and 372. That is, the control circuits 301 and 302 monitor the clock signal from the external clock 450, and when the clock signal fails, PWM control is performed by the internal clocks 371 and 372. As a result, even when the external clock 450 has failed, the drive control of the motor by the PWM control is continued.

The driver circuits 351, 352 are typically gate drivers. The drive circuits 351 and 352 generate control signals (for example, gate control signals) for controlling the switching operation of the switching elements in the first inverter 101 and the second inverter 102 based on the PWM signals, and supply the generated control signals to the switching elements. The microcontrollers 341, 342 can have the function of a driver circuit 351, 352. In this case, the drive circuits 351, 352 are omitted.

The ROMs 361, 362 are, for example, writable memory (e.g., PROM), rewritable memory (e.g., flash memory), or read-only memory. The ROMs 361, 362 store control programs including instruction sets for causing the microcontrollers 341, 342 to control the inverters 101, 102, and the like. For example, the control program is temporarily expanded in a RAM (not shown) at the time of startup. Hereinafter, a specific example of the operation of the motor drive unit 1000 will be described, and mainly, specific examples of the operation of the inverters 101 and 102 will be described.

The control circuits 301, 302 drive the motor 200 by performing three-phase energization control using both the first inverter 101 and the second inverter 102. Specifically, control circuits 301 and 302 perform three-phase energization control by performing switching control of switching elements of first inverter 101 and switching elements of second inverter 102. Fig. 3 is a diagram showing the values of currents flowing through the respective coils of the respective phases of the motor 200.

Fig. 3 illustrates current waveforms (sine waves) obtained by plotting current values flowing through the respective coils of the U-phase, V-phase, and W-phase of the motor 200 when the first inverter 101 and the second inverter 102 are controlled in accordance with three-phase energization control. The horizontal axis of fig. 3 shows the motor electrical angle (deg) and the vertical axis shows the current value (a). I is_pkThe maximum current value (peak current value) of each phase is shown. In addition to the sine waves illustrated in fig. 3, the inverters 101 and 102 include, for example, a sine waveThe motor 200 may also be driven using a rectangular wave.

The current waveform illustrated in fig. 3 is generated by applying a voltage having a waveform corresponding to such a current waveform to the motor 200. Such a voltage is generated by switching the switching elements of the first inverter 101 and the switching elements of the second inverter 102 at a high speed of, for example, 20kHz by PWM control. Fig. 4 and 5 are diagrams schematically showing the switching operation under PWM control, fig. 4 showing a state where voltage is applied, and fig. 5 showing a state where application is stopped.

In fig. 4 and 5, for example, U-phase branches among the branches that the inverters 101, 102 have are shown. As described above, the U-phase branch includes the high-side switching device 113H and the low-side switching device 113L on the first inverter 101 side, and the high-side switching device 116H and the low-side switching device 116L on the second inverter 102 side.

The high-side switching device 113H and the low-side switching device 113L on the first inverter 101 side are not in an on state at the same time, and when one is in an on state, the other is in an off state. Similarly, the high-side switching device 116H and the low-side switching device 116L on the second inverter 102 side are not turned on at the same time.

When a voltage is applied to the windings of the motor 200, the high- side switching elements 113H and 116H are turned on in one of the two inverters 101 and 102 (the second inverter 102 in the case of fig. 4), and the low- side switching elements 113L and 116L are turned on in the other inverter (the first inverter 101 in the case of fig. 4). As a result, a current flows from the one side to the other side as indicated by arrows in the drawing.

When the application is stopped, all the switching elements are turned off. Immediately after the off state, a circulating current from the motor 200 flows through the capacitors (105 and 106 in fig. 2), but no current flows thereafter. In addition, the circulating current does not contribute to the torque of the motor 200.

In the two inverters 101 and 102, the state in which the voltage shown in fig. 4 is applied and the state in which the application is stopped shown in fig. 5 are repeated at high speed. The repetition of the voltage application and the application stop in the inverters 101, 102 is performed in accordance with the PWM signals generated by the microcontrollers 341, 342 of the control circuits 301, 302. Fig. 6 is a diagram showing the PWM signal.

The PWM signal is a 2-value pulse signal, and a first value showing voltage application and a second value showing application stop are alternately generated. The pulses of the PWM signal are repeated with a period T0, the period T0 being divided into a first value of duration T1 and a second value of duration T2.

Since the PWM signal is a high-frequency signal such as 20kHz as described above, the period T0 is a short period such as 50 μ sec. Therefore, the effective voltage (effective voltage) applied to the motor 200 becomes a voltage averaged in the period T0, and the ratio (duty ratio) of the period T0 to the duration T1 of the first value is equal to the ratio of the power supply voltage to the effective voltage. The effective voltage is, for example, a voltage that changes with time in accordance with a current value that changes as in the current waveform shown in fig. 3. This temporal variation of the effective voltage is achieved by controlling the duty cycle of the PWM signal by the microcontroller 341, 342.

The two microcontrollers 341, 342 each generate a carrier signal having a period T0, and generate a PWM signal from the carrier signal, and the period T0 in each microcontroller 341, 342 is synchronized with the period of a clock signal supplied from an external clock. Therefore, since the microcontrollers 341 and 342 are synchronized with the period T0 (i.e., synchronized with the signal frequency) and the inverters 101 and 102 are synchronized with the frequency of the switching operation, torque ripple caused by variation in the period T0 can be suppressed.

(hardware construction of Motor drive Unit 1000)

Next, a hardware configuration of the motor drive unit 1000 will be described. Fig. 7 is a diagram schematically showing the hardware configuration of the motor drive unit 1000.

The motor drive unit 1000 includes, as a hardware configuration: the above-mentioned motor 200; a first mounting substrate 1001; a second mounting substrate 1002; a housing 1003; and connectors 1004, 1005.

One end 210 and the other end 220 of the coil protrude from the motor 200 and extend toward the second mounting substrate 1002. One end 210 and the other end 220 of the coil are connected to the second mounting substrate 1002.

Substrate surfaces of the first mounting substrate 1001 and the second mounting substrate 1002 face each other. The rotation shaft of the motor 200 extends in a direction facing the substrate surface. The first mounting substrate 1001, the second mounting substrate 1002, and the motor 200 are housed in a case 1003, and their positions are fixed.

The connectors 1004, 1005 are mounted on the first mounting substrate 1001 and the second mounting substrate 1002. Power lines from both the first power supply 403 and the second power supply 404 are connected to the connectors 1004 and 1005.

The first mounting board 1001 is a so-called control board, and the first control circuit 301 and the second control circuit 302 are mounted on the first mounting board 1001. Further, an external clock 450 is mounted on the first mounting board 1001, and the first control circuit 301 and the second control circuit 302 are arranged symmetrically (line-symmetrical or point-symmetrical) with respect to the external clock 450. The first control circuit 301 and the second control circuit 302 are connected to the external clock 450 through wirings having the same length as each other, and are supplied with clock signals. Therefore, the phase offset between the clock signals supplied to the first control circuit 301 and the second control circuit 302 is reduced, and the phases of the PWM control of the first control circuit 301 and the second control circuit 302 are synchronized.

(software construction)

Next, the software configuration of the control circuits 301 and 302 will be described. Fig. 8 is a diagram schematically showing the software configuration of the control circuits 301 and 302.

In the present embodiment, when the motor drive unit 1000 performs communication with an external device or the like, the first control circuit 301 of the two control circuits 301 and 302 performs communication or the like mainly. Therefore, the software structures of the two control circuits 301, 302 are different.

Fig. 8 shows a main program 1101 embedded in the first control circuit 301 and a sub-program 1102 embedded in the second control circuit 302. The first control circuit 301 and the second control circuit 302 operate according to programs 1101 and 1102, respectively.

The main program 1101 includes an initial setting section 1103 that allows communication with an external device or the like, and a drive control section 1104 that controls the first inverter 101 or the like. The sub program 1102 includes a drive control section 1106 similar to the main program 1101, and includes a time adjustment section 1105.

Time adjustment section 1105 approximates the start time of the carrier signal in main routine 1101 to the time at which the carrier signal of PWM control starts in accordance with the PWM carrier start instruction embedded in drive control section 1106. Specifically, the time adjustment section 1105 has the number of instructions for causing the second control circuit 302 to pass the same time as the execution time required for the instructions included in the initial setting section 1103 of the main program 1101 to be executed in the first control circuit 301.

In other words, the program (for example, the sub-program 1102) of one of the first control circuit 301 and the second control circuit 302 includes a program portion for time adjustment between a command at the head of the program and a PWM carrier start command for starting a carrier signal for PWM control. The program portion for the time adjustment has a command number for making a difference between the start time of the one carrier signal and the start time of the other carrier signal coincide with an integral multiple (for example, 0 times in the present embodiment) of the period of the carrier signal.

The main program 1101 and the sub program 1102 are executed from the command at the beginning of the program by turning on the power in the motor drive unit 1000. While the initial setting unit 1103 of the main program 1101 is executed by the first control circuit 302, the time adjustment unit 1105 of the sub program 1102 is executed by the second control circuit 302. As a result, the start timings of the drive control sections 1104 and 1106 coincide with each other in the first control circuit 301 and the second control circuit 302, and the start timings of the carrier signals accompanying the execution of the PWM carrier start command also coincide with each other. Therefore, in the first control circuit 301 and the second control circuit 302, the phase shift of the carrier signals from each other is reduced, and the phases of the PWM control are synchronized. Next, a modified example of the present embodiment will be described. Fig. 9 is a diagram showing a circuit configuration of the motor drive unit 1000 in a modification in which circuit wirings are different. In the modification shown in fig. 9, the grounded ends of the first inverter 101 and the second inverter 102 are separated from each other. Even with such a separate structure, torque ripple occurs when the frequency of the carrier signal varies. Therefore, in the modification shown in fig. 9, the frequencies of the carrier signals in both the first inverter 101 and the second inverter 102 are synchronized with each other by the common external clock 450, and the torque ripple is suppressed. In this modification as well, the phase of the carrier signal is synchronized by the hardware configuration shown in fig. 7 and the software configuration shown in fig. 8, thereby further suppressing the torque ripple.

(embodiment of Power steering apparatus)

Vehicles such as automobiles generally include a power steering device. The power steering apparatus generates an assist torque for assisting a steering torque of a steering system generated by a driver operating a steering handle. The assist torque is generated by the assist torque mechanism, and the burden of the operation of the driver can be reduced. For example, the assist torque mechanism is constituted by a steering torque sensor, an ECU, a motor, a speed reduction mechanism, and the like. The steering torque sensor detects a steering torque in the steering system. The ECU generates a drive signal based on a detection signal of the steering torque sensor. The motor generates an assist torque corresponding to the steering torque based on the drive signal, and transmits the assist torque to the steering system via the speed reduction mechanism.

The motor drive unit 1000 of the above embodiment is applied to a power steering apparatus. Fig. 10 is a diagram schematically showing the configuration of an electric power steering apparatus 2000 according to the present embodiment. The electric power steering apparatus 2000 includes a steering system 520 and an assist torque mechanism 540.

The steering system 520 includes, for example, a steering handle 521, a steering shaft 522 (also referred to as a "steering column"), universal shaft joints 523A and 523B, and a rotary shaft 524 (also referred to as a "pinion shaft" or an "input shaft").

The steering system 520 includes, for example, a rack and pinion mechanism 525, a rack shaft 526, left and right ball joints 552A and 552B, tie rods 527A and 527B, knuckles 528A and 528B, and left and right steered wheels (e.g., left and right front wheels) 529A and 529B.

The steering handle 521 is connected to the rotating shaft 524 via the steering shaft 522 and universal shaft joints 523A and 523B. A rack shaft 526 is connected to the rotating shaft 524 via a rack and pinion mechanism 525. The rack and pinion mechanism 525 has a pinion 531 provided on the rotating shaft 524 and a rack 532 provided on the rack shaft 526. A right steering wheel 529A is connected to a right end of the rack shaft 526 via a ball joint 552A, a tie rod 527A, and a knuckle 528A in this order. Similarly to the right side, a left steered wheel 529B is connected to the left end of the rack shaft 526 via a ball joint 552B, a tie rod 527B, and a knuckle 528B in this order. Here, the right and left sides correspond to the right and left sides, respectively, as viewed by a driver sitting on the seat.

According to the steering system 520, a steering torque is generated by the driver operating the steering handle 521 and is transmitted to the left and right steering wheels 529A and 529B via the rack and pinion mechanism 525. This allows the driver to operate the left and right steerable wheels 529A and 529B.

The assist torque mechanism 540 includes, for example, a steering torque sensor 541, an ECU542, a motor 543, a reduction mechanism 544, and an electric power supply device 545. The assist torque mechanism 540 applies assist torque to the steering system 520 from the steering handle 521 to the left and right steered wheels 529A and 529B. In addition, the assist torque is sometimes referred to as "additional torque".

As the ECU542, for example, the control circuits 301 and 302 shown in fig. 1 and the like are used. As the power supply device 545, for example, inverters 101 and 102 shown in fig. 1 and the like are used. As the motor 543, for example, the motor 200 shown in fig. 1 and the like is used. When the ECU542, the motor 543, and the power supply device 545 constitute a unit generally called an "electromechanical integrated motor", for example, a motor drive unit 1000 having a hardware configuration shown in fig. 7 is preferably used as the unit. A mechanism including elements other than the ECU542, the motor 543, and the power supply device 545 among the elements shown in fig. 10 corresponds to an example of the power steering mechanism driven by the motor 543.

The steering torque sensor 541 detects a steering torque of the steering system 520 applied by the steering handle 521. The ECU542 generates a drive signal for driving the motor 543 based on a detection signal (hereinafter referred to as "torque signal") from the steering torque sensor 541. The motor 543 generates an assist torque corresponding to the steering torque based on the drive signal. The assist torque is transmitted to the rotary shaft 524 of the steering system 520 via the speed reduction mechanism 544. The reduction mechanism 544 is, for example, a worm gear mechanism. The assist torque is also transmitted from the rotating shaft 524 to the rack and pinion mechanism 525.

The power steering apparatus 2000 is classified into a pinion assist type, a rack assist type, a column assist type, and the like according to a portion where assist torque is applied to the steering system 520. Fig. 10 shows a pinion assist type power steering apparatus 2000. However, the power steering device 2000 is also applicable to a rack assist type, a column assist type, and the like.

Not only a torque signal, for example, a vehicle speed signal, may be input to the ECU 542. The microcontroller of the ECU542 can PWM-control the motor 543 based on the torque signal, the vehicle speed signal, and the like.

The ECU542 sets a target current value based on at least the torque signal. Preferably, ECU542 sets the target current value in consideration of a vehicle speed signal detected by a vehicle speed sensor, and further, in consideration of a rotor rotation signal detected by an angle sensor. The ECU542 can control a drive signal, i.e., a drive current, of the motor 543 so that an actual current value detected by a current sensor (see fig. 1) matches a target current value.

According to the power steering apparatus 2000, the left and right steering wheels 529A and 529B can be operated by the rack shaft 526 using a composite torque obtained by adding the assist torque of the motor 543 to the steering torque of the driver. In particular, by using the motor drive unit 1000 of the above embodiment, smooth power assist with less torque ripple can be realized.

Here, although the power steering apparatus is given as an example of a method of using the drive control apparatus and the drive apparatus according to the present invention, the method of using the drive control apparatus and the drive apparatus according to the present invention is not limited to the above method, and can be used in a wide range of applications such as pumps and compressors.

The above-described embodiments should be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the claims, not by the embodiments described above, and includes all modifications equivalent in meaning and scope to the claims.

Description of the symbols

101. 102: an inverter; 200: a motor; 301. 302: a control circuit; 311. 312: a power supply circuit; 321. 322: an angle sensor; 331. 332: an input circuit; 341. 342: a microcontroller; 351. 352: a drive circuit; 361. 362: a ROM; 401. 402, a step of: a current sensor; 403. 404: a power source; 450: an external clock; 1000: a motor drive unit; 1001. 1002: a mounting substrate; 2000: provided is a power steering device.

Claims (6)

1. A drive control device for controlling the driving of a motor, comprising:

a first inverter connected to one end of a winding of the motor;

a second inverter connected to the other end opposite to the one end;

a first control circuit that performs PWM control on the first inverter;

a second control circuit that performs PWM control on the second inverter; and

and a common clock that supplies a clock signal for PWM control to both the first control circuit and the second control circuit.

2. The drive control apparatus according to claim 1,

the first control circuit and the second control circuit each include an internal clock, and the first control circuit and the second control circuit monitor a clock signal from the common clock and perform PWM control by the internal clock in the case where the clock signal fails.

3. The drive control apparatus according to claim 1 or 2,

the first control circuit and the second control circuit operate according to a program, and the program of one of the first control circuit and the second control circuit includes a program portion for time adjustment having a number of instructions for matching a difference between a start time of the carrier signal and a start time of the carrier signal with respect to the other of the first control circuit and the second control circuit with an integral multiple of a cycle of the carrier signal between a command at a beginning of the program and a command of the carrier signal for starting PWM control.

4. The drive control apparatus according to any one of claims 1 to 3,

the first control circuit and the second control circuit are connected to the common clock through wirings having the same length as each other, and are supplied with clock signals.

5. A drive device is provided with:

the drive control apparatus according to any one of claims 1 to 4; and

a motor, the driving of which is controlled by the drive control means.

6. A power steering device is provided with:

the drive control apparatus according to any one of claims 1 to 4;

a motor, the driving of which is controlled by the drive control means; and

a power steering mechanism driven by the motor.

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