EP1766758A2 - Methode pour commander un moteur electrique pour reduire les emissions emi - Google Patents

Methode pour commander un moteur electrique pour reduire les emissions emi

Info

Publication number
EP1766758A2
EP1766758A2 EP05760256A EP05760256A EP1766758A2 EP 1766758 A2 EP1766758 A2 EP 1766758A2 EP 05760256 A EP05760256 A EP 05760256A EP 05760256 A EP05760256 A EP 05760256A EP 1766758 A2 EP1766758 A2 EP 1766758A2
Authority
EP
European Patent Office
Prior art keywords
motor
phase
angle
conduction angle
speed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05760256A
Other languages
German (de)
English (en)
Inventor
James B. Eskritt
Joel E. Kuehner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Infineon Technologies Americas Corp
Original Assignee
International Rectifier Corp USA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US11/149,101 external-priority patent/US7202622B2/en
Application filed by International Rectifier Corp USA filed Critical International Rectifier Corp USA
Publication of EP1766758A2 publication Critical patent/EP1766758A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/04—Arrangements or methods for the control of AC motors characterised by a control method other than vector control specially adapted for damping motor oscillations, e.g. for reducing hunting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/065—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/26—Power factor control [PFC]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/50—Reduction of harmonics

Definitions

  • the present invention relates to electrical motor drives and, in particular, to electric motors driven by switched converters which convert a dc potential to one or more phases of pulsed current to drive the motor.
  • the motor can be, for example, a brashless dc motor having Hall sensors to control the commutation.
  • This invention further relates to a power steering device that generates auxiliary steering power for driving the steering mechanism of a vehicle by means of the oil pressure that is generated by a pump which is driven by electric power.
  • the invention further relates to reducing EMI (electromagnetic interference) in a motor drive for controlling an electric motor.
  • FIG. 1 shows a typical three phase motor drive from a dc bus.
  • the motor may be a brushless DC motor having a permanent magnet rotor and a stator comprising stator coils fed with switched pulsed phase drive signals.
  • the dc bus voltage is provided to an inverter 100 comprising three half bridges comprising transistors (e.g., MOSFETs, IGBTs, bipolar devices) gated by signals AH, AL, BH, BL and CH, CL.
  • the high and low side devices are each connected in series across the bus and the output of each device comprises one of the three phases, U, V and W.
  • Each of the switching devices is controlled by a controller 200, which receives Hall signals controlling the commutation times from the electric motor 300.
  • the gate drive signals AH, AL, BH, BL and CH, CL are provided to the respective switches of the inverter 100.
  • a Hall signal is provided from the motor for each phase, one of which is shown. Only one of each of the gate drive high and low signals is shown. In a typical application, the Hall signals provide a signal for controlling the switching of the switches in the inverter and thus the motor commutation.
  • a typical motor drive is shown in Fig. 2 having a 120° conduction angle.
  • the gate drives can be pulse width modulated (PWM) as shown by the low gate drive signal in Fig. 2.
  • the gate drive signal switch events occur when the Hall transitions occur and any phase advance of the gate drive signal is determined solely by the physical placement of the position of the Hall effect sensors in the motor.
  • the conduction angle is forced to be 120° or 180°.
  • the effective voltage at the outputs of the half bridges is controlled by varying the duty cycle of the PWM.
  • the pulse width modulation may be done on the low side or the high side or on both the high side and the low side. In Fig. 2, only one phase is shown. The other two phases are shifted by 120°.
  • Figure 3 shows another example of a typical motor drive having 180° conduction angle.
  • the high or low side signals can be pulse width modulated or both can be pulse width modulated.
  • An object of the present invention is to provide a means for achieving a variable phase advance and/or conduction angle requiring no mechanical changes to the motor to obtain phase advance and change the conduction angle, thereby resulting in improved motor control. It is a further object of the invention to provide an improved electric power steering system for a vehicle.
  • a power steering device that assists the operation of the steering wheel of a vehicle by supplying operating oil from the oil pump to the power cylinder that is joined to the steering mechanism has been known.
  • the oil pump is driven by an electric motor, with the auxiliary steering power which is in conformity with the speed of the motor rotation being generated by a power cylinder.
  • a torsion bar that generates torsion which is in conformity with the direction and size of the steering torque which has been provided by the steering wheel and an oil pressure control valve which changes its opening size in conformity with the direction and the size of the torsion of the torsion bar are incorporated.
  • This oil pressure control valve is provided in the oil pressure system between the oil pump and the power cylinder and it causes an auxiliary steering power which is in conformity with the steering torque to be generated from the power cylinder.
  • the drive control of the electric power motor is carried out on the basis of the steering angular speed of the steering wheel.
  • the steering angle speed is obtained on the basis of the output of the steering angle sensor that has been provided in connection with the steering wheel, and the target rotary speed of the electric power motor is set based on this steering angle rate. Voltage is supplied to the electric motor in such that this target rotary speed may be achieved.
  • the electric motor a triple-phase brushless motor is ordinarily used.
  • the triple-phase brushless motor comprises a stator which has field coils for the U phase, the V phase and the W phase, a rotor with a fixed permanent magnet that receives the repulsive magnetic field from the field coils and Hall sensors for detecting the rotation position of this rotor.
  • Three Hall sensors are provided at an interval of 120 degrees as an electric angle in conformity with the U phase, the V phase and the W phase.
  • the triple-phase brushless motor is driven in accordance with the conventional 120 degree power system in the ordinary case. This 120 degree power system is shown in Figure 13.
  • the Hall signals that are outputted by the Hall sensors of the U phase, the V phase and the W phase deviate from each other by 120 degrees in phase.
  • the electrical power is passed during a period corresponding to an electric angle of 120 degrees to the U phase, the V phase and the W phase in turn so as to synchronize with the Hall signals of the U phase, the V phase and the W phase.
  • PWM pulse width modulation
  • Figure 14 shows the relationship between the rotary speed of the rotor and the output torque in the triple-phase brushless motor. As is shown in Figure 14, it is known that the output torque decreases along with an increase in the rotary speed.
  • regulations have been imposed by governmental bodies that require EMI emissions to be below present levels, usually dependent on frequency.
  • a problem solved by the present invention is the reduction of EMI by the motor controller.
  • conduction angle control of a brushless DC motor reduces the number of switching events in the power stage, thereby reducing the amount of electromagnetic emissions.
  • This allows the use of smaller, lower cost EMI filtering components and allows the controller to meet regulation requirements.
  • Brushless DC motor drives produce significant amounts of electromagnetic interference due to the switching voltages and current involved.
  • Each application has EMI limits determined by the operating environment and relevant regulations.
  • EMI filtering components are typically included in a motor drive design to try to meet the EMI limits. The size and cost of the filtering components are determined by the amount of attenuation required to meet the limits.
  • a system and method for achieving a variable phase advance and/or a variable conduction angle in a motor drive system which decreases EMI generation is described herein.
  • a method for reducing EMI emissions in the control of an electric motor supplied by a switching inverter fed by a DC bus comprising controlling a phase advance of a conduction angle period during which a phase of the motor is fed power by the inverter to control the conduction angle to control the speed of the motor, thereby to reduce the number of switching operations of the inverter and thereby reduce EMI.
  • the invention provides advantages in that increasing the phase advance and/or conduction angle gives a higher achievable speed for any given torque. That is, the power is increased. Further, increasing the conduction angle reduces torque ripple.
  • a method for controlling an electric motor having at least one sensor output for determining a switching instant for a switch of a switching inverter controlling a conduction angle determining a conduction time during a revolution of the motor comprising; receiving the sensor output; and advancing a switching-on time of a switch of the switching converter connecting a d-c bus voltage to a motor phase drive input by a phase angle prior to the next sensor output determining the switching instant.
  • a purpose of this invention lies in offering a power steering device which is capable of obtaining a high rotary speed in the medium low torque range of the electric motor and which does not bring about a drastic rise in manufacturing costs.
  • the invention for achieving the aforementioned objective is a power steering device that generates an auxiliary steering power by oil pressure that is generated by a pump which is driven by an electric motor, the motor having a conduction angle during which electrical power is provided to at least one motor phase
  • the power steering device comprising a rotary angle detector for detecting the rotary angle of said electric motor, a steering angular speed sensor for detecting a steering angular speed of a steering operating member, a drive target value rotational speed setting device for setting a drive target value rotational speed of said electric motor in relation to an output signal of the steering angular speed sensor, a drive signal generator for producing a drive signal for driving said electric motor and an angle setting device for determining a phase advance angle of the drive signal with respect to the rotary angle that is detected by said rotary angle detector on the basis of the drive target value rotational speed which is set by said drive target value rotational speed setting device, thereby changing the conduction angle.
  • this power steering device generates reduced EMI.
  • the phase advance angle of the drive signal is set in conformity with the drive target value rotational speed of the electric power motor (such as a brushless motor), with the conduction angle being changed accordingly.
  • the electric motor is a triple-phase brushless motor, with said triple-phase brushless motor being driven according to the 120 degree conduction angle method, the timing for the start of the electricity passing to the field coils of the U phase, the V phase and the W phase is variably set for the phase of the output signal of the rotary angle detector (such as a Hall sensor) corresponding to the U phase, the V phase and the W phase.
  • the motor generating voltage (back emf) becomes small, thereby increasing the output torque.
  • this invention it becomes possible to increase the rotary speed in the medium low torque ranges without drastically changing the design of the motor or the design of the system as a whole. Accordingly, there will be no drastic increase in the cost. Since it is possible to exercise control so as to set a suitable phase advance angle (the minimum phase advance angle required) for the required motor rotary speed, it becomes possible to control the major problems in the control of the phase advance angle (such as a reduction in permanent magnetism or lowering of efficiency).
  • the phase advance angle setting means sets a certain fixed phase advance angle irrespective of said drive target value at the time when the electricity passage to the electric motor is in an unsaturated state but sets the phase advance angle on the basis of the drive target value which is set by the the drive target setting device at the time when power passing to the electric motor is saturated.
  • a phase advance angle which is in conformity with the drive target value can be set only after the 120 power passage has been saturated, (for example, it may be set at zero degrees) and, by carrying out PWM control within the power passing period of 120 degrees, for instance, both the low speed rotation control and the medium-speed rotational control of the power motor can be controlled.
  • Fig. 1 shows a generalized block diagram of a motor controller
  • Fig. 2 shows a typical prior art motor drive control scheme
  • Fig. 3 shows another prior art motor drive control scheme
  • Fig. 4 shows a motor drive control scheme in accordance with the invention providing variable phase advance and/or conduction angle
  • Fig. 5 shows several timing charts for motor drive signals for various cases of variable phase advance, fixed phase advance and conduction angle
  • Fig. 6 shows a speed controller in accordance with the invention that selectively uses variable phase advance/conduction angle and pulse width modulation.
  • FIG. 7 is a conceptual drawing showing the basic constitution of a power steering device according to one example of this invention.
  • Fig. 8 is a block diagram showing the functional constitution of the electric control unit in the above-described power steering device.
  • Fig. 9 is a characteristic chart showing the relationship between the steering angle speed and the target rotary speed.
  • Fig. 10 is a chart shown for the purpose of explaining the power driving method for operating the electric motor.
  • Fig. 11 is a figure showing the relationship between the phase advance angle and the target rotary speed.
  • Fig. 12 is characteristics figure showing the relationship of the torque versus the rotary speed of the electric motor.
  • Fig. 13 is a time chart presented for the purpose of explaining the conventional 120 degree conduction angle system.
  • Fig. 10 is a block diagram showing the functional constitution of the electric control unit in the above-described power steering device.
  • Fig. 9 is a characteristic chart showing the relationship between the steering angle speed and the target rotary speed.
  • Fig. 10 is a chart shown for the
  • FIG. 14 is a drawing showing the relationship between the rotary speed and the output torque in the three-phase brushless motor.
  • Fig. 1 shows conducted emissions of a brushless DC motor drive operating at 70A DC bus current while being pulse width modulated.
  • Fig. 16 shows the motor drive of Fig. 15 operating at 70 A DC bus current with no PWM switching occurring but using phase advance to achieve motor speed control.
  • Fig. 4 shows gate drive high and gate drive low signals for one motor phase, as well as the ideal and physical Hall signals from the motor.
  • the ideal Hall signal is placed such that if 120° conduction angle were used with 0° phase advance, the switching instants would occur at the same time as the Hall signal transitions. This is shown in Fig. 4 by the dashed line x. If no phase advance is provided, the switching instants for the high drive signal would coincide with the rising edge of the ideal Hall signal.
  • the physical Hall signal may be offset (advanced) from the ideal Hall signal by some amount, which can be 0°, or some value greater than 0°.
  • An exemplary physical Hall signal is shown in Fig. 4.
  • the variable phase advance (from the ideal Hall signal) is indicated in Fig. 4.
  • Fig. 4 shows that the gate drive high signal is switched on some variable phase amount prior to the ideal Hall transition and some variable amount prior to the physical Hall signal transition.
  • the conduction angle may vary between 120° and 180°.
  • the phase advance is variable.
  • the phase advance and conduction angle may be independently adjustable although in practice a co-dependency is useful.
  • a variable advance may be added to the conduction angle to provide an additional amount of conduction angle.
  • the conduction angle equals 120° plus the amount of variable advance a in the scheme shown.
  • the total phase advance p equals a fixed amount of advance k plus the variable advance a.
  • phase advance and conduction angle are shown as co-dependent in Fig. 4, they need not be.
  • a phase advance can be employed merely to shift the conduction period, but the conduction angle remains constant.
  • the switching instants of the gate drive signals are not constrained to coincide with the Hall transitions.
  • a software algorithm can place the switching instants arbitrarily relative to the Hall sensor edges.
  • pulse width modulation may or may not be used depending upon the application. Adjusting the phase advance and/or conduction angle may be used to regulate the speed or current in certain situations, with or without PWM.
  • phase advance which means the switching transition of the gate signal is before the Hall signal transition
  • a software algorithm can use the prior Hall transition to cause the advance prior to the next corresponding Hall signal transition.
  • increasing phase advance and conduction angle provides a higher achievable speed for any given torque. That is, power is increased.
  • the increase in conduction angle also reduces torque ripple.
  • Table I was recorded for a typical electric motor at 13.5 volts and 2.48 Nm torque. 00 I
  • p k + a , k ⁇ p ⁇ (k + 60°)
  • c 120° + a, 120° ⁇ c ⁇ 180° 0° ⁇ a ⁇ 60° p
  • k 15° 120° conduction:
  • variable advance is also equal to the additional conduction angle.
  • the fixed advance shifts the conduction angle period, while the variable advance increases the conduction angle.
  • the above scheme has the advantages that it is simple, it results in higher efficiency and it provides the possibility of placing the Hall sensor such that a number of switching instants will align with the Hall edges. This may improve the accuracy and simplicity of the software algorithm.
  • Figure 5 shows several examples of the control scheme according to the present invention. In Fig.
  • variable advance equals 0°
  • total phase advance equals the fixed phase advance k
  • conduction angle equals 120°
  • Fig. 5B the variable phase advance is between 0 and 60°.
  • the total phase advance equals the fixed advance k plus the variable advance a and the conduction angle equals 120° plus the variable advance a.
  • Fig. 5C the variable advance equals 60°
  • the total phase advance equals fixed advance k plus 60°
  • the conduction angle equals 180°.
  • the ideal and possible physical Hall signals for a single phase are as shown at the top and bottom of Fig. 5, respectively.
  • the result is that the turn off instants for each corresponding switch (for each conduction angle) is at the same point regardless of the amount of variable advance. That is, the turn off instant for switch AH is the same for each of the three conduction angles. Similarly, the turn off instant for the switches AL for each scheme is at the same time, likewise for the switches BH, BL, CH and CL.
  • the Hall effect sensors can be positioned as shown by the possible physical Hall signal shown at the bottom of the plot, so that turn off instants always align with a Hall transition. The same would be true of the two other phases. This simplifies the software algorithm for controlling the switching of the drive transistors in each half bridge, thus simplifying the software for controlling commutation.
  • Figure 6 shows a speed control utilizing the invention.
  • losses due to switching in the power devices of the converter are significant. Losses occur when the transistors and the diodes switch. Thus, there are significant losses when pulse width modulating. Due to these losses, instead of pulse width modulating, when variable advance is greater than 0, a full duty cycle (100% PWM) may be used.
  • the speed controller as shown in Fig. 6 can be provided that leaves the duty cycle at 100% but varies variable advance a in order to regulate motor speed.
  • a gate drive comprising a inverter 100 is provided which provides the three phases to the motor 300.
  • the Hall signals are provided to a controller 200' which includes a commutator 200 A and a pulse width modulator 200B.
  • the commutator 200A is provided with a signal comprising the variable amount of advance a , either 0 or some amount of advance for motor control.
  • the pulse width modulator 200B is provided with a signal controlling the duty cycle, either an amount of duty cycle less than 100% or 100%.
  • a switch 400 provides a variable advance a equal to 0 or a variable advance from a controller 2 to the commutator.
  • Switch 400 also provides a duty cycle comprising either the output of a controller 1 comprising a variable duty cycle or 100% duty cycle to the pulse width modulator, as shown.
  • Switch 400 may be controlled by a software controller and could comprise a transistor switching circuit. Controllers 1 and 2 are provided with a speed reference signal (Speed Ref.) which determines the desired speed.
  • Speed Ref. speed reference signal
  • a feedback signal 4000 is derived from the position sensor(s) and provided to the controllers 1 and 2 as an indication of the actual motor speed.
  • Controller 1 is used when the desired speed is reached with 120° conduction angle and less than 100% duty cycle. If the current drawn by the motor is too high with 120° conduction and a 100% duty cycle, this scheme is also used.
  • variable advance a equals 0 as shown in Fig. 6.
  • Controller 2 is used if the desired speed cannot be reached with 120° conduction angle and 100% duty cycle provided the current draw is not too high. Accordingly, when controller 2 is used, a variable advance a greater than 0 is provided to the commutator 200A with 100% pulse width modulation (full on during conduction angle).
  • Controller 1 may include both speed and current control. Hysteresis may be needed when switching between the two controllers.
  • the invention accordingly comprises a system for providing high efficiency motor control and higher operating speeds at any given torque, thereby increasing power. Further, the increased conduction angle reduces the torque ripple. For example, actual test results for a typical electric motor with INm of torque, show a 75% increase in current results in a 77% increase in motor speed. Table II shows some actual test results. TABLE ⁇ MOTOR SPEED (RPM)
  • FIG. 7 is a conceptual figure indicating the basic constitution of a power steering device according to an example of this invention.
  • This steering device is arranged relative to the steering mechanism 1 of the vehicle, with an auxiliary steering power being provided given to this mechanism 1.
  • the steering mechanism 1 comprises for example, a steering wheel 2 which is operated by the operator, a steering shaft 3 which is linked to this steering wheel 2, a pinion gear 4 coupled to the steering shaft 3, and a rack gear 5 a which is engaged with the pinion gear 5, with a rack shaft 5 being extended in the right and left directions.
  • tie rods 6 are joined and the tie rods 6 are linked to a knuckle arm 7 that supports the wheels FL and FR at the right and at the left as steerable wheels.
  • the knuckle arm 7 is provided in such a fashion as to revolve around the king pin 8.
  • the above arrangement is exemplary only.
  • Other forms of steering gears and other components can be provided, as known to those of skill in the art. In the above-described construction, when the steering wheel 2 is operated and the steering shaft 3 is rotated, the rotation is converted into a linear movement along the right-left direction of the wheel by the pinion gear 4 and the rack shaft 5.
  • This straight- line movement is converted into a revolution amount around the king pin of the knuckle arm 7, with the result that the steering of the right and left wheels FL and FR is achieved.
  • a torsion bar 9 that produces torsion in conformity with the direction and the size of the steering torque that is added to the steering wheel 2 and an oil pressure control valve 23 whose opening changes in conformity with the direction and the size of the torsion of the torsion bar 9 are incorporated.
  • the oil pressure control valve 23 is connected to a power cylinder 20 that provides the auxiliary steering power to the steering mechanism 1.
  • the power cylinder 20 has a piston 21 that is integrally provided on the rack shaft 5 and a pair of cylinder chambers 20a and 20b that have been divided by the piston 21.
  • the cylinder chambers 20a and 20b are connected with the oil pressure control valve 23 through the oil supply and return routes 22a and 22b respectively.
  • the oil pressure control valve 23 is further provided on an oil circulation route 24 that passes through a reserve tank 25 and an oil pump 26.
  • the oil pump 26 is driven by a motor M(27) of the electromotive type; it draws the operating oil which is stored in the reservoir tank 25 to supply same to the oil pressure control valve 23. The excess operating oil is returned to the reservoir tank 25 from the oil pressure control valve 23 through the oil circulation route 24.
  • the oil pressure control valve 23 supplies the operating oil to either the cylinder chamber 20a or cylinder chamber 20b of the power cylinder 20 through either the oil supply or return route 22a and 22b in the case where torsion is impressed to the torsion bar 9 in one direction. In the event that torsion is impressed to the torsion bar 9 in the other direction, further, it supplies the operating oil to the other of the cylinder chambers 20a and 20b through the other of the oil supply or return routes 22a and 22b. In the case where no torsion or torsion is scarcely impressed to the torsion bar 9, the oil pressure control valve 23 will be in the so-called equilibrium state and the operating oil circulates in the oil circulation route 24 without being supplied to the power cylinder.
  • the electric motor 27 consists, for example, of a triple-phase brushless motor and it is controlled by an electronic control unit 30 through a drive circuit 28.
  • the drive circuit 28 comprises, for instance, a power transistor bridge circuit. It supplies electric power from a battery 40 as an electric power source to the electric motor 27 in accordance with the control signal that is provided by an electronic control unit 30.
  • the electronic control unit 30 includes a micro-computer which is activated upon receiving a power supply from the battery 40.
  • This micro-computer comprises a CPU31, a RAM 32 that provides the work area for the CPU 31, a ROM 33 that has memorized the data for control as well as the action program of the CPU 31, and a bus 34 for the mutual connection of the CPU 31, RAM 32 and ROM 33.
  • steering angle data as outputted from the steering angle sensor 11 is provided.
  • the steering angle sensor 11 is provided in relation to the steering wheel 2.
  • the CPU 31 calculates the steering speed that corresponds to its time differential value.
  • An electric current detection signal from an electric current sensor 12 that detects the electric current that flows to the electric motor 27 and a detection signal from the Hall sensor 15 as a rotor position sensor for the detection of the rotor position of the electric power motor 27 are provided to the electronic control unit 30.
  • a wheel speed signal that is outputted from the wheel speed sensor 13 is given to the electronic control unit 30.
  • the wheel speed sensor 13 may be a sensor that directly detects the wheel speed (proportional to vehicle speed) or the wheel speed may be obtained by calculation on the basis of the output pulse of the wheel speed sensor that has been provided in relation to the wheel.
  • the electronic control unit 30 controls the electric power motor 27 on the basis of the steering angle data, the current data and the wheel speed data that are given from the steering angle sensor 11, the current sensor 12 and the wheel speed sensor 13 respectively.
  • Figure 8 is a block diagram showing the construction of the electronic control unit as viewed from its functional standpoint.
  • the electronic control unit 30 substantially possesses a plurality of functional means that are realized through the execution of a program stored in ROM 33 by the CPU 31.
  • the electronic control unit 30 thus comprises a steering angular speed operating part 41 for the calculation of the steering angular speed on the basis of the output signal of the steering angular sensor 11 and a target rotary speed setting part 42 that sets the target rotary speed R of the electric motor 27 on the basis of the wheel speed as detected by the wheel speed sensor 13 as well as the steering angle speed calculated by the steering angular speed operating part 41.
  • the electronic control unit 30 is provided with a motor driving control part 45 that controls and drives the electric power motor 27 so as to achieve the target rotary speed R as set by the target rotary speed setting part 42.
  • the motor drive control part 45 generates a drive signal for achieving the target rotary speed R on the basis of the motor electric current that is detected by the electric current sensor 12 and provides this drive signal to the drive circuit.
  • the electric motor 27 is provided with a stator that has a U-phase field coil 27U, a V-phase field coil 27V and a W-phase field coil 27W and a rotor with a fixed permanent magnet that receives a repulsion field from these field coils 27U, 27V and 27 W, with the rotary angle of this rotor detected by the Hall sensor 15.
  • the Hall sensor 15 comprises the Hall sensors 15U, 15V and 15W that have been provided in conformity with the U phase, the V phase and the W phase.
  • the current sensor 12 whose purpose it is to detect the electric current that flows to the electric motor 27 is equipped with electric current sensors 12U, 12V and 12W that detect the electric currents that flow to the U phase, the V phase and the W phase respectively.
  • the output signals of the electric current sensors 12U, 12V and 12W and the Hall sensors 15U, 15V and 15W are suitably amplified and provided to the motor drive control part 45.
  • the current sensor 12 can be implemented as a single current sensor coupled to the DC bus.
  • the drive circuit 28 comprises a series circuit of a pair of field effect transistors UH and UL that correspond to the U phase, a pair of field effect transistors VH and VL that correspond to the V phase and a pair of field effect transistors WH and WL that correspond to the W phase coupled in parallel across the battery 40.
  • the U phase field coil 27U of the electric motor 27 is connected to a connecting point between the field effect transistor UH and UL
  • the V phase field coil 27 V is connected to a connecting point between the field effect transistors VH and VL
  • the W phase field coil 27W is connected to a connective point between the field effect transistors WH and WL.
  • the motor drive control part 45 brings the field effect transistors UH, VH and WH into the ON state in this order during a certain period of electric angle and, at the same time, controls the rotation of the electric motor 27 by providing a drive signal consisting of the PWM pulses for the electric field effect transistors UL, VL and WL.
  • the motor drive control part 45 comprises a PWM duty cycle setting part 46 for setting the PWM duty cycle corresponding to the target rotary speed R that is set up by the target rotary speed setting part 42, a phase advance angle setting part 47 for setting the phase advance angle ⁇ ⁇ which correspond to the target rotary speed that is set likewise by the target rotary speed setting part 42 and a drive signal producing part 48 that produces the drive signals to be given to the field effect transistors UH, UL, VH, VL, WH and WL of the drive circuit 28 on the basis of the phase advance angle ⁇ ⁇ that is set by the phase advance angle setting part 47 as well as the PWM duty cycles that are set by the PWM duty setting part 46.
  • Figure 9 is a figure showing the relation between the steering angular speed and the target rotary speed as set by the target rotary speed setting part 42.
  • the target rotary speed R is set between the lower limit RI and the user limit R2 so that it will monotonously increase (the increase being linear in this form of execution) in the range of zero being no larger than V( ⁇ ), which is no larger than VT (VT being a threshold value) regarding the steering angular speed V( ⁇ ).
  • the target rotary speed setting apart 42 variously sets the incline of the target rotary speed R as compared with the steering angle speed B( ⁇ ) on the basis of the wheel speed as is shown in Figure 3.
  • the threshold value VT is variously set in accordance with the wheel speed range.
  • the threshold value is set higher when the wheel speed becomes higher, i.e., when the vehicle is moving faster. Accordingly, the target rotary speed R will be set lower as the wheel speed becomes higher, with a consequence that the auxiliary steering power becomes smaller. In this manner, wheel-speed responsive control is carried out for generating a suitable steering auxiliary power in conformity with the speed of the vehicle.
  • Figure 10 is a time chart presented for the purpose of explaining the method of passing the electric current for driving the electric motor 27.
  • Figure 10(a) shows the U- phase Hall signal that is outputted by the Hall sensor 15U and Figure 10(b) shows the V-phase Hall signal that the Hall sensor 15V outputs.
  • Figure 10(c) shows the W-phase Hall signal that the Hall sensor 15W outputs.
  • Figure 10(d) shows the drive signal wave-form that is provided to the field effect transistor UH
  • Figure 10(e) shows the waveform of the drive signal that is provided to the field effect transistor VH
  • Figure 10(f) shows the drive signal waveform that is provided to the electric field effect transistor WH.
  • the U phase Hall signal, the V phase Hall signal and the W phase Hall signal assume the waveforms phase-delayed by an electric angle of 120 degrees each.
  • the drive signal producing part 48 produces the drive signals that basically follow the 120 degree power passing system.
  • the drive signal that is provided to the field effect transistor UH rises in advance of the U-phase Hall signal and, after being held in an ON state only during the period of an electric angle obtained by adding the phase advance angle ⁇ ⁇ to 120 degrees, it is turned back to the OFF state in synchronization with a Hall signal.
  • the drive signal that is provided to the field effect transistor VH rises in advance of the rising edge of the V-phase Hall signal and, after being held in the ON state only during the period of the electric angle obtained by adding the phase advance angle ⁇ ⁇ to 120 degrees, it is turned to the OFF state in synchronization with a Hall signal.
  • the drive signal of the field effect transistor WH rises to the ON state in advance of the leading edge of the W-phase Hall signal and, at the same time, it is kept in the ON state only during the period of the electric angle obtained by adding the phase advance angle ⁇ ⁇ to 120 degrees, followed by turnback to the OFF state in synchronization with a Hall signal. While these controls are being carried out, the pulse width control signal for the duty ratios set at the PWM duty setting part 46 is provided to the field effect transistors UL, VL and WL.
  • the phase advance angle setting part 47 is for setting the advance angle of the phase of the drive signal as compared with the Hall signal on the basis of the target rotary speed R.
  • the phase advance angle setting part 47 sets the phase advance angle ⁇ ⁇ at zero insofar as the PWM duty setting part 46 sets a PWM duty of less than 100 percent.
  • the drive signal producing part 48 produces a drive signal that follows the ordinary 120 degree conduction angle system.
  • the phase advance angle setting part 47 variously sets the phase advance angle ⁇ ⁇ in accordance with the target rotary speed R.
  • the drive signal producing part 48 brings the field effect transistor UH, VH and WH into the ON state at the timing where the phase has been advanced by the phase advance angle ⁇ ⁇ as compared with the Hall signal.
  • the power passing (conduction angle) time will become the time that corresponds to 120 degrees plus ⁇ ⁇ , with the power passing time becoming longer by the time corresponding to the phase advance angle ⁇ ⁇ .
  • the phase advance angle ⁇ ⁇ that is set by the phase advance angle setting part 47 and the target rotary speed R that is set by the target rotary speed setting part 42.
  • the phase advance angle setting part 47 sets the phase advance angle ⁇ ⁇ in such a way as to monotonously increase from zero to 60 degrees in the target rotary speed R region between 4,000 rpm and 5,000 rpm.
  • the phase advance angle ⁇ ⁇ may be set in such a fashion as will increase linearly along with an increase in the target rotary speed R or the change in the phase advance angle ⁇ ⁇ as compared with the target rotary speed r may become a non-linear change.
  • phase advance angle ⁇ ⁇ be set at 60 degrees. If a phase advance angle ⁇ ⁇ that exceeds 60 degrees is set, the field effect transistors UH, UL, VH, VL, WH and WL are set on simultaneously, thereby damaging the power element of the drive circuit 28 (field effect transistors UH, UL, VH, VL, WH and WL).
  • Figure 12 is a characteristic figure showing the relation of the torque against the rotary speed of the electric motor 27. As has been shown in Formula (1) above, when the rotary speed ⁇ increases, the motor electric current I is reduced due to the motor generated induced voltage kco that is produced thereby, with a result that the torque that is proportional to this motor current decreases.
  • FIG. 6 shows conducted emissions of a brushless DC motor drive operating at 70A DC bus current while under PWM control. The emissions are compared with the EMI limit lines for a particular application. It can be seen that while employing PWM control, the low frequency emissions are more than 15 dB above the limit.
  • Figure 16 shows the same motor drive operating at 70A DC bus current but with no PWM switching occurring.
  • the conducted emissions now also meet the low frequency limits, showing the advantage of controlling conduction angle and not employing PWM.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Abstract

L'invention concerne une méthode pour réduire les émissions d'interférences électromagnétiques (EMI), dans le dispositif de commande d'un moteur électrique alimenté par un convertisseur continu/alternatif à commutations alimenté par un bus CC. Cette méthode consiste à commander une avance de phase d'une période angulaire de conduction pendant laquelle une phase du moteur est alimentée en puissance par le convertisseur continu/alternatif, pour commander l'angle de conduction pour commander la vitesse du moteur, ce qui permet de réduire le nombre d'opérations de commutation du convertisseur, et ainsi de réduire les émissions EMI.
EP05760256A 2004-06-10 2005-06-10 Methode pour commander un moteur electrique pour reduire les emissions emi Withdrawn EP1766758A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US57851104P 2004-06-10 2004-06-10
US11/149,101 US7202622B2 (en) 2002-04-30 2005-06-09 Method for controlling an electric motor to reduce EMI
PCT/US2005/020758 WO2005124976A2 (fr) 2003-04-28 2005-06-10 Methode pour commander un moteur electrique pour reduire les emissions emi

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EP1766758A2 true EP1766758A2 (fr) 2007-03-28

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US8030788B2 (en) * 2008-12-31 2011-10-04 General Electric Company Method and systems for an engine starter/generator

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JP3243977B2 (ja) * 1995-08-18 2002-01-07 国産電機株式会社 電動車両用ブラシレス直流電動機の制御方法
US6392418B1 (en) * 1999-09-16 2002-05-21 Delphi Technologies, Inc. Torque current comparison for current reasonableness diagnostics in a permanent magnet electric machine
US6566829B1 (en) * 2000-09-07 2003-05-20 Delphi Technologies, Inc. Method and apparatus for torque control of a machine
US6549871B1 (en) * 2001-05-03 2003-04-15 Delphi Technologies, Inc. Current estimation for an electric machine
US6694287B2 (en) * 2001-08-30 2004-02-17 Delphi Technologies, Inc. Phase angle diagnostics for sinusoidal controlled electric machine
JP4226236B2 (ja) * 2001-09-07 2009-02-18 パナソニック株式会社 モータ制御装置
US6738718B2 (en) * 2002-03-27 2004-05-18 Motorola, Inc. Method and apparatus for measuring torque and flux current in a synchronous motor
US7157878B2 (en) * 2002-11-19 2007-01-02 Delphi Technologies, Inc. Transient compensation voltage estimation for feedforward sinusoidal brushless motor control
JP2004266904A (ja) * 2003-02-28 2004-09-24 Matsushita Electric Ind Co Ltd モータの運転制御装置
JP4352860B2 (ja) * 2003-11-07 2009-10-28 トヨタ自動車株式会社 電動機の制御装置

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KR20070032779A (ko) 2007-03-22
KR100848185B1 (ko) 2008-07-23

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