JP3688437B2 - Electric motor drive device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor drive device for a vehicle that drives a motor mounted on the vehicle, and more particularly, to a motor drive device for a vehicle that prevents a PWM (pulse width modulation) signal that drives the motor from being mixed into the radio as noise. .
[0002]
[Prior art]
Conventional motor drive devices for vehicles include an electric power steering device mounted on the vehicle, a four-wheel steering rear wheel steering device, an automatic steering device, a power window device, and the like. This is performed at a constant voltage, and PWM (pulse width modulation) drive is used as one means for changing the current flowing through the electric motor.
[0003]
Note that the PWM drive frequency is preferably set in the range of, for example, 16 KHz to 20 KHz in consideration of preventing the PWM drive signal from being heard by a passenger and having a small switching loss in PWM drive. .
[0004]
[Problems to be solved by the invention]
In the conventional motor drive device for a vehicle, the PWM drive frequency is fixed at, for example, 18 KHz, and the PWM drive waveform is a pulse, and therefore includes a harmonic component of the fundamental frequency (18 KHz). However, there is a problem that it is received as an AM (amplitude modulation) signal of a car radio and can be heard as noise.
[0005]
For example, assuming that the driver is listening to a cultural broadcast (channel frequency 1134 KHz) during operation, if the PWM drive frequency is set to 18 KHz, the harmonic component (18 KHz × 18 KHz × 63 = 1134 KHz) matches the channel frequency 1134 KHz and is heard as noise from the car radio.
[0006]
Similarly, even when listening to a radio of another channel frequency, if the harmonic component of the PWM drive frequency is close to the channel frequency, it will be heard as noise from the car radio.
[0007]
In order to prevent the phenomenon that the harmonic component of the PWM drive frequency is received by the AM radio and becomes a noise, attempts have been made to attenuate the harmonic component by dulling the pulse waveform of the PWM drive signal. When dulled, the switching loss of the motor drive circuit (for example, a bridge circuit composed of the switching element FET) increases and heat generation from the FET increases. There is a problem that the product cost increases due to an increase in the number of parts selected and the number of parts, such as reducing the size and connecting FETs in parallel.
[0008]
The present invention has been made to solve such a problem. The object of the present invention is to change the drive frequency of the PWM drive signal in accordance with the channel frequency of the car radio, and to cause the car radio due to the harmonic component of the PWM drive frequency. It is to prevent noise jumping in.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the control means of the motor drive device for a vehicle according to the present invention comprises: a receiving means for receiving external specific information; and a frequency change for changing the drive frequency of the PWM control signal based on a signal from the receiving means. And the receiving means comprises code detecting means for detecting the code of the external specific information .
[0010]
Since the control means of the motor drive device for a vehicle according to the present invention includes receiving means for receiving the external identification information and frequency changing means for changing the drive frequency of the PWM control signal based on a signal from the receiving means, The external specific information is received, the drive frequency of the PWM control signal is changed according to the external specific information, and the harmonic component of the PWM drive frequency can be set to a frequency away from the radio channel frequency.
[0012]
Since the receiving means according to the present invention includes the code detecting means for detecting the code of the external specific information, the specific means corresponding to the radio channel frequency from the external specific information (diagnostic signal) supplied from the vehicle fault diagnosis machine. The code can be detected.
[0013]
According to another aspect of the present invention, there is provided a motor drive apparatus for a vehicle, comprising: an electric motor; target current setting means for setting a target current signal based on a motor start signal; and drive control means for generating a PWM control signal based on the target current signal. Control means and motor drive means for PWM driving the motor based on the PWM control signal, the control means receiving means for receiving the external identification information, and the PWM control signal based on the signal from the reception means Frequency change means for changing the drive frequency is provided, and the external identification information is characterized by a diagnostic signal supplied from an external diagnostic machine .
[0015]
Furthermore, the frequency changing means according to the present invention is characterized by comprising frequency division number setting means for setting the frequency division number of the reference clock.
[0016]
Since the frequency changing means according to the present invention includes the frequency dividing number setting means for setting the frequency dividing number of the reference clock, the frequency changing means is changed based on the received external specific information to change the drive frequency of the PWM control signal. Can be changed.
[0018]
Since the external identification information according to the present invention is a diagnostic signal supplied from an external diagnostic machine, the drive frequency of the PWM control signal can be changed using the interface of the external diagnostic machine and the electronic control unit (ECU). .
[0019]
Furthermore, the external identification information according to the present invention is a channel signal received by a radio receiver.
[0020]
Since the external identification information according to the present invention is a channel signal received by the radio receiver, the drive frequency of the PWM control signal can be automatically changed inside the electric motor drive device of the vehicle.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
In the present invention, the drive frequency of a PWM drive signal for driving an electric motor mounted on a vehicle such as an electric power steering device, a four-wheel steering rear wheel steering device, an automatic steering device, and a power window device is set to a car radio (in particular, AM radio) is changed according to the channel frequency received, and the harmonic component of the PWM drive frequency becomes a frequency close to the channel frequency of the radio broadcast and is prevented from being received as noise by the car radio.
[0022]
FIG. 1 is a block diagram of a main part of a motor drive device for a vehicle according to the present invention.
In FIG. 1, the motor drive device 1 for a vehicle includes an electric motor 10, a control unit 15, an electric motor drive unit 16, and an electric motor current detection unit 18, and the electric motor 10 is based on an electric motor activation signal K _S supplied from the electric motor activation unit 12. Drive.
[0023]
The motor starting means 12 is configured to start the motor 10, for example, a steering torque sensor in an electric power steering device and a window opening / closing switch in a power window.
[0024]
The control means 15 is composed of various calculation functions, processing functions, and memories based on a microprocessor, and includes a target current signal setting means 21, a deviation calculation means 22, a drive control means 23, a receiving means 24, and a frequency changing means 25.
[0025]
Target current signal setting means 21 constituted by a memory such as a ROM, may be set the target current signal data I _MS corresponding to the set motor activation signal K _S, based on the pre-experimental values or design values, the motor starts When the motor start signal K _S is supplied from the means 12, the target current signal data _IMS is read and the target current signal _IMS is supplied to the deviation calculating means 22.
[0026]
Deviation calculation means 22, constituted by subtraction function of the subtractor or the software control, the target current signal I _MS supplied from the target current signal setting unit 21, motor current detecting means 18 corresponding to the detected motor current I _M A deviation ΔI (= I _M −I _MO ) from the motor current signal I _MO is calculated, and the deviation signal ΔI is supplied to the drive control means 23.
[0027]
The drive control unit 23 includes a PID controller 26 and a control signal generation unit 27.
The PID controller 26 has a proportional (P) calculation function, an integral (I) calculation function, and a differentiation (D) calculation function, and performs proportional control, integral control and differential control on the deviation signal ΔI supplied from the deviation calculating means 22. After that, the synthesized signal I _C is provided to the control signal generator 27.
[0028]
The control signal generating means 27 includes an on signal generating means, a PWM signal generating means, etc., and an electric motor control signal composed of an on signal and a PWM signal having a predetermined duty ratio based on the composite signal I _C provided from the PID controller 26. V _O is supplied to the motor driving means 16.
[0029]
FIG. 2 is a block diagram showing the principal part of one embodiment of the control signal generating means according to the present invention.
In FIG. 2, the control signal generating means 27 includes a timer means 27A, an ON signal generating means 27B, a duty ratio setting means 27C, a frequency dividing means 27D, and a PWM signal generating means 27E.
[0030]
Timer means 27A is constituted by clock means such as a timer, and starts counting the trigger composite signal I _C provided from the PID controller 26, for example, on signal generating means 27B and PWM timer signal T _O H level The signal is supplied to the signal generating means 27E.
Incidentally, the timer signal T _O is stopped when the combined signal I _C disappears.
[0031]
On signal generating means 27B is constructed by a buffer or the like, H level when the timer signal T _O in response to the timer signal T _O supplied from the timer means 27A is at H level, the timer signal T _O is at the L level In this case, the L level ON signal V _ON is output as a part of the motor control signal V _O.
[0032]
Duty ratio setting means 27C sets the pulse duty ratio corresponding to the magnitude of the composite signal I _C provided from the PID controller 26 provides a pulse duty ratio signal P _D to the PWM signal generating means 27E.
[0033]
Frequency dividing means 27D has, for example, a divider circuit constituted by a counter, etc., divides the reference clock of the control unit 15 to a predetermined number to provide a clock pulse F _D of the frequency obtained by dividing the PWM signal generating means 27E .
Incidentally, the frequency division number of the frequency dividing means 27D is set based on the frequency division number signal N _D supplied from the frequency changing means 25 which will be described later.
[0034]
PWM signal generating means 27E constitutes the signal combiner, and synthesized based on the frequency division number signal N _D supplied from the pulse duty ratio signal P _D and divider means 27D is provided from the duty ratio setting unit 27C, A PWM signal V _PWM having a duty corresponding to the combined signal I _C and a drive frequency (for example, 16 to 20 KHz) corresponding to the frequency division number signal N _D is output as a part of the motor control signal V _O.
[0035]
The receiving unit 24 includes a code (symbol) detecting unit or a frequency detecting unit, and external identification information including a diagnostic signal of a code (symbol) supplied from an external failure diagnosing device 19 or a channel frequency received by the car radio. based on J _G, it detects the frequency data of the external identification information J _G, provides frequency data S _D to the frequency converter 25.
The external failure diagnosis device 19 is a device that is installed in a vehicle maintenance shop or the like and inspects a vehicle failure.
[0036]
FIG. 3 is a block diagram showing the principal part of an embodiment of the receiving means according to the present invention.
In FIG. 3, the receiving means 24 comprises a timing pulse generating means 31, a code storage means 32, a data access means 33, and a code detection means 28 provided with a code conversion means 34.
[0037]
The timing pulse generating means 31 is constituted by a signal generator that divides the reference clock for driving the control means 15 and generates a timing pulse of a predetermined frequency, and supplies the timing pulse _TP to the code storage means 32.
[0038]
The code storage means 32 includes a rewritable memory such as a RAM, and a code corresponding to the radio channel frequency included in the external identification information J _G supplied from the external failure diagnosing device 19 is sent to the timing pulse T _P. There were held and stored in the period being fed, to the data access means 33 holds the code (the code) as code data D _C.
[0039]
In addition, when another external specific information J _G is supplied during the period in which the timing pulse _TP is supplied, the code storage unit 32 uses the code included in the external specific information J _G as a new code. Store and hold as (symbol).
[0040]
Note that the code (symbol) included in the external identification information J _G is composed of, for example, a binary code corresponding to the radio channel frequency.
[0041]
The data access means 33 has a data access function, sends the code data D _C supplied from the code storage means 32 to the code conversion means 34, and receives the frequency data _SD corresponding to the code data D _C from the code conversion means 34. Read out and supply to the frequency changing means 25.
[0042]
The code conversion means 34 is composed of a memory such as a ROM, stores frequency data _SD corresponding to the code data D _C in advance, and when the code data D _C is supplied from the data access means 33, the code data D _The frequency data _SD corresponding to _C is supplied to the data access means 33.
[0043]
The frequency data S _D is set to a fundamental frequency at which the N-th order and N + 1-order or N−1-order harmonics of the PWM drive frequency are farthest from the radio channel frequency corresponding to the code data D _C , and N The next and (N + 1) th order or (N-1) th order harmonics are not received near the radio channel frequency.
[0044]
FIG. 4 is a block diagram showing the principal part of another embodiment of the receiving means according to the present invention.
In FIG. 4, the receiving unit 30 includes a frequency detecting unit 29 including a frequency determining unit 36, a frequency storing unit 37, and a frequency converting unit 38.
[0045]
The frequency discriminating means 36 is composed of, for example, a band-pass filter, a detector or the like of a plurality of frequency bands. When the external specific information J _G matching the radio channel frequency (for example, AM band) is supplied from the car radio 20, The channel frequency is detected and, for example, an H level frequency discrimination signal _DF is provided to the frequency storage means 37.
[0046]
The frequency storage means 37 is composed of a rewritable RAM or the like, is detected by the frequency discrimination means 36, stores and holds a frequency discrimination signal _DF corresponding to the channel frequency, and frequency conversion means as frequency data F _O 38.
[0047]
The frequency conversion means 38 is composed of a memory such as a ROM, stores frequency data _SD corresponding to the frequency data F _O of the radio channel frequency in advance, and the frequency data F _O is supplied from the frequency storage means 37. Then, the frequency data _SD corresponding to the frequency data F _O is supplied to the frequency changing means 25.
[0048]
The frequency data S _D is set to a fundamental frequency at which the Nth order and N + 1st order or N−1th order harmonics of the PWM drive frequency are farthest from the radio channel frequency that matches the frequency data F _O. The next and (N + 1) th order or (N-1) th order harmonics are not received near the radio channel frequency.
[0049]
The frequency conversion means 25 includes a frequency division number setting means constituted by a memory such as a ROM, and the frequency data _SD supplied in advance from the code detection means 28 shown in FIG. 3 or the frequency detection means 29 shown in FIG. stores correspondence data of the reference clock frequency f _C (16MHz~32MHz) the division and frequency division number as the harmonic components of the PWM driving frequency is not a vicinity of the channel frequency of the radio which is formed by N _D means 15 When the frequency data _SD is supplied, the corresponding frequency dividing number N _D is read out and the frequency dividing number data N _D is supplied to the frequency dividing unit 27D of the control signal generating unit 27 shown in FIG.
[0050]
The frequency division number N _D set by the frequency changing means 25 is the Nth harmonic of the PWM drive frequency f _PWM obtained by dividing the reference clock frequency f _R by the frequency N _D and the (N + 1) th harmonic or ( N-1) The harmonics satisfy the relationship of Equation 1 to the radio channel frequency f _C as much as possible.
[0051]
[Expression 1]
f _C = {(f _R / N _D ) × N + (f _R / N _D ) × (N−1)} / 2
Or
f _C = {(f _R / N _D ) × N + (f _R / N _D ) × (N + 1)} / 2
[0052]
Further, PWM driving frequency f _PWM to the reference clock frequency f _R obtained by dividing the division number N _D is higher than the lowest frequency outside the audible frequency 16 KHz, the switching loss of the switching elements constituting the motor drive circuit is small 20KHz Set to a lower value.
[0053]
Motor drive means 16, for example constituted by a bridge circuit composed of switching elements of four power FET (field effect transistor), a pair of two power FET in the diagonal of the bridge circuit based on motor control signal V _O each PWM (pulse width modulation) driving, and outputs a drive motor voltage V _M to be turned on drive for driving the electric motor 10.
[0054]
The motor current detection unit 18 detects the motor current I _M that actually flows through the motor 10 and feeds back (negative feedback) the motor current signal I _MO corresponding to the motor current I _M to the control unit 15.
[0055]
Is fed back to the control unit 15 motor current signal I _MO is a deviation between the target current signal _{I MS ΔI (= I MS -I} MO) is calculated by the deviation calculating means 22, the motor current signal I _MO is a target current signal I It is controlled by the drive control means 23 so that _MS becomes equal and the deviation ΔI becomes 0 (I _MS = I _MO ).
[0056]
Thus, the control means 15 of the motor drive device 1 for a vehicle according to the present invention drives the PWM control signal based on the receiving means 24 for receiving the external identification information J _G and the signal _SD from the receiving means 24. Since the frequency changing means 25 for changing the frequency is provided, the external specific information J _G is received, the drive frequency of the PWM control signal is changed according to the external specific information J _G, and the harmonic component of the PWM drive frequency is radio. It can be set to a frequency away from the channel frequency.
[0057]
As a result, even when the electric motor mounted on the vehicle is PWM-driven, it is possible to prevent noise caused by radio reception of the harmonic component of the PWM drive frequency in the vicinity of the radio channel frequency.
[0058]
FIG. 5 is an overall configuration diagram of an electric power steering apparatus to which the present invention is applied.
In FIG. 5, an electric power steering device 40 is connected to a steering shaft 2 provided integrally with a steering wheel 17 via a connecting shaft 3 having universal joints 3a and 3b. A manual steering force generating means 6 is configured by being connected to the pinion 5 a of the pinion mechanism 5.
[0059]
The rack shaft 7 is provided with rack teeth 7a meshing with the pinion 5a, and the rack shaft 7 reciprocates by the meshing is connected to left and right front wheels 9 as rolling wheels via tie rods 8 at both ends thereof.
[0060]
In this way, when steering the steering wheel 17, the front wheel 9 is rolled by manual steering through the normal rack and pinion type manual steering force generating means 6 to change the direction of the vehicle.
[0061]
In order to reduce the steering force generated by the manual steering force generating means 6, an electric motor 10 that supplies a steering assist force is arranged coaxially with the rack shaft 7 and via a ball screw mechanism 11 provided coaxially with the rack shaft 7. It is converted into thrust and applied to the rack shaft 7 (ball screw shaft 11a).
[0062]
A steering torque sensor 12 for detecting the direction and magnitude of the manual steering torque of the driver constituting the motor starting means 12 is arranged in the steering gear box 4, and an analog corresponding to the steering torque detected by the steering torque sensor 12. A steering torque signal T _S (motor start signal K _S ) as an electrical signal is provided to the control means 15.
[0063]
As described with reference to FIG. 1, the control means 15 is composed of various calculation means, processing means, signal generation means, memory, etc. based on a microprocessor, and an electric motor control signal V _O (for example, corresponding to the steering torque signal T _S (for example, A hybrid signal of an ON signal and a PWM control signal is generated to drive and control the motor driving means 16.
[0064]
Further, as described in FIG. 1, the control unit 15 receives the specific code code as the diagnostic signal supplied from the external failure diagnosing device 19 as the external specific information J _G or the radio receiver (car radio) 20. Receiving means 24 for receiving the channel frequency, and frequency changing means 25 for changing the drive frequency of the PWM control signal of the motor control signal V _O based on the external identification information J _G received by the receiving means 24 are provided.
[0065]
The motor drive means 16 that drives the motor 10 and the motor current detection means 18 that detects the motor current I _M , converts it into a corresponding motor current signal I _MO , and feeds it back to the control means 15 are the same as those shown in FIG. Therefore, explanation is omitted.
[0066]
In FIG. 5, the motor drive device of the vehicle includes a control unit 15, a motor drive unit 16, a motor current detection unit 18, and the motor 10.
[0067]
As described above, by applying the electric motor driving device for a vehicle according to the present invention to the electric power steering device, it is possible to prevent noise mixed in the car radio due to the PWM driving frequency for PWM driving the electric motor.
[0068]
FIG. 5 shows an example in which the motor drive device for a vehicle according to the present invention is applied to an electric power steering device. However, the present invention is similarly applied to a rear wheel steering device, an automatic steering device, and a power window device for four-wheel steering. be able to.
[0069]
【The invention's effect】
The control means for the motor drive device for a vehicle according to the present invention comprises a receiving means for receiving the external specifying information and a frequency changing means for changing the drive frequency of the PWM control signal based on a signal from the receiving means. Since the information is received, the drive frequency of the PWM control signal is changed according to this external specific information, and the harmonic component of the PWM drive frequency can be set to a frequency away from the channel frequency of the radio, the PWM control signal It is possible to prevent the harmonic component of the driving frequency from being heard as noise from the radio near the radio channel frequency.
[0070]
Further, the receiving means according to the present invention comprises code detecting means for detecting a code of external specific information, and specified specific information corresponding to a radio channel frequency from external specific information (diagnostic signal) supplied from a vehicle fault diagnosis machine. Since the code can be detected, the PWM drive frequency can be easily set so as not to jump into a radio channel frequently used at a repair shop or service station as noise.
[0071]
Furthermore, the receiving means according to the present invention includes a frequency detecting means for detecting the frequency of the external specific information, and can detect the channel frequency of the car radio as the external specific information. Even in this case, a PWM drive frequency that does not jump into the radio channel as noise can be automatically set.
[0072]
The frequency changing means according to the present invention further comprises frequency dividing number setting means for setting the frequency dividing number of the reference clock, and changes the frequency dividing number based on the received external specific information to change the drive frequency of the PWM control signal. Since it can be changed, it is possible to prevent the harmonic component of the drive frequency of the PWM control signal from being heard as noise from the radio near the radio channel frequency.
[0073]
Furthermore, the external identification information according to the present invention is a diagnostic signal supplied from an external diagnostic machine, and the drive frequency of the PWM control signal can be changed using the interface of the external diagnostic machine and the electronic control unit (ECU). Therefore, radio noise can be prevented without significantly changing the external diagnostic device or the electronic control unit (ECU).
[0074]
Further, the external specific information according to the present invention is a channel signal received by the radio receiver, and the drive frequency of the PWM control signal can be automatically changed inside the motor drive device, so that the radio is not limited to any region. Noise prevention can be realized.
[0075]
Therefore, it is possible to provide a motor drive device for a vehicle that can prevent noise to the car radio due to a harmonic component of the PWM drive frequency that can be easily adjusted with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a block diagram of an essential part of an electric motor driving apparatus for a vehicle according to the present invention. FIG. 2 is a block diagram of an essential part of an embodiment of a control signal generating means according to the present invention. FIG. 4 is a block diagram of the main part of another embodiment of the receiving means according to the present invention. FIG. 5 is an overall block diagram of an electric power steering apparatus to which the invention is applied. Explanation of]
DESCRIPTION OF SYMBOLS 1 ... Vehicle electric motor drive device, 2 ... Steering shaft, 3 ... Connection shaft, 4 ... Steering gear box, 5 ... Rack & pinion mechanism, 6 ... Manual steering force generation means, 7 ... Rack shaft, 8 ... Tie rod, 9 ... Left and right front wheels, 10. ... target current signal setting means, 22 ... deviation calculating means, 23 ... drive control means, 24, 30 ... receiving means, 25 ... frequency changing means, 26 ... PID controller, 27 ... control signal generating means, 27A ... timer means, 27B ... ON signal generation means, 27C ... Duty ratio setting means, 27D ... Frequency division means, 27E ... PWM signal generation means, 28 ... Code detection means, 29 Frequency detecting means, 31 ... timing pulse generating means, 32 ... code storing means, 33 ... data access means, 34 ... code converting means, 36 ... frequency discriminating means, 37 ... frequency storing means, 38 ... frequency converting means, 40 ... electrical Power steering device, I _C ... composite signal, I _MO ... motor current signal, I _M ... motor current, I _MS ... target current signal, ΔI (= I _MS -I _MO ) ... deviation signal, J _G ... external identification information, K _S ... motor start signal, N _D ... frequency division signal, S _D ... frequency data, V _O ... motor control signal, V _ON ... on signal, V _PWM ... PWM signal.

Claims (5)

An electric motor; target current setting means for setting a target current signal based on a motor start signal; control means having drive control means for generating a PWM control signal based on the target current signal; and the electric motor based on the PWM control signal. In a motor drive device for a vehicle, comprising:
The control means includes a receiving means for receiving external specific information, and a frequency changing means for changing the drive frequency of the PWM control signal based on a signal from the receiving means ,
The receiving means includes code detecting means for detecting a code of external specific information,
An electric motor drive device for a vehicle. Timing pulse generating means for setting the timing for detecting the code of the external specific information;
Code storage means for storing as a new code when another external specific information is supplied during a period in which the timing pulse is supplied from the timing pulse generating means;
The motor drive apparatus for a vehicle according to claim 1, comprising: An electric motor; target current setting means for setting a target current signal based on a motor start signal; control means having drive control means for generating a PWM control signal based on the target current signal; and the electric motor based on the PWM control signal. In a motor drive device for a vehicle, comprising:
The control means includes a receiving means for receiving external specific information, and a frequency changing means for changing the drive frequency of the PWM control signal based on a signal from the receiving means,
The motor drive device for a vehicle, wherein the external identification information is a diagnostic signal supplied from an external diagnostic machine . It said frequency changing means includes an electric motor drive device of the vehicle according to claim 1 or 3, wherein further comprising a frequency division number setting means for setting a frequency division number of the reference clock. External specifying information, the motor driving apparatus for a vehicle according to claim 1 or 3, wherein the radio receiver is a channel signal received.

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