JP2005184966A - Drive controller for dc commutatorless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive controller for a DC commutatorless motor which can control torque continuously even in case that abnormality occurs in a current sensor, in a drive controller for a motor. <P>SOLUTION: The drive controller for a DC commutatorless motor is provided with a current detection means which detects each phase of currents, an abnormality detection means which detects the abnormality of the current detection means, and a current value estimating means which estimates the current value of the phase where the abnormality is detected on the basis of the current value of the phase excepting the phase where the abnormality is detected by the abnormality detection means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a drive control device for a DC non-commutator motor, and more particularly to a drive control device for a DC non-commutator motor that performs torque control with a motor.

Conventionally, for example, a technique disclosed in Patent Document 1 has been disclosed as a drive control device for a DC non-commutator motor. In this publication, when a three-phase brushless motor is used for motor drive control, a current sensor is provided in two phases, and the remaining one-phase current value is estimated and calculated from the current values detected in two phases. Torque control is performed by driving the motor based on the current value.
JP 2001-128479 A (see FIG. 2).

  However, the above-described DC non-commutator motor drive control device has the following problems. When current sensors are provided for two of the three phases, if one of the two phases fails, the current value of the phase without the current sensor cannot be estimated by calculation, and torque control continues. There is a problem that can not be done.

  The present invention has been made paying attention to the above problems, and in a DC non-commutator motor drive control device, torque control can be continuously performed even when an abnormality occurs in a current sensor. An object of the present invention is to provide a drive control device for a DC non-commutator motor.

  In order to achieve the above object, according to the present invention, in a drive control device for a DC commutator motor, a current detection unit that detects a current of each phase, an abnormality detection unit that detects an abnormality of the current detection unit, and an abnormality detection unit Current value estimating means for estimating a current value of a phase where an abnormality is detected is provided based on a current value of a phase other than the phase where the abnormality is detected.

  Therefore, even when an abnormality occurs in any one of the current sensors, torque control can be continuously performed by using the current values detected by the current sensors of the remaining phases.

  Hereinafter, the best mode for realizing a drive control device for a DC non-commutator motor according to the present invention will be described based on a first embodiment shown in the drawings.

FIG. 1 is a system diagram showing the overall configuration of a drive control device for a DC non-commutator motor in this embodiment.
The power steering system consists of steering wheel SW, steering shaft 1, torque sensor TS, rack L, pinion P, power steering mechanism 2, external gear type bidirectional pump 3 driven by electric motor M, fail-safe valve 4, driver The warning lamp WL and a control unit (ECU) 20 for notifying that a failure has occurred in the steering system.

  The bidirectional pump 3 as a hydraulic pressure source of the power steering mechanism 2 is provided in hydraulic pipes 7a and 7b that communicate the first cylinder chamber 2a and the second cylinder chamber 2b of the power cylinder 21. When the driver operates the steering wheel SW, the rotation direction of the electric motor M is switched in accordance with the operation direction, and the oil between the first cylinder chamber 2a and the second cylinder chamber 2b is supplied and discharged to thereby change the driver's direction. Assist steering force. Specifically, when the steering wheel SW in the figure is steered to the right, the electric motor 6a is driven in the direction in which the hydraulic pressure is supplied from the first cylinder chamber 2a to the first cylinder chamber 2b, so that it moves integrally with the rack L. Assisting the piston 21 to the first cylinder chamber 2a side.

  A bypass circuit 6 is provided between the hydraulic pipe 7a and the hydraulic pipe 7b to connect the first cylinder chamber 2a and the second cylinder chamber 2b without the bidirectional pump 3 therebetween. On the bypass circuit 6, an electronically controlled fail-safe valve 4 that operates based on a command signal from a control unit (ECU) 20 is provided.

  The fail-safe valve 4 uses a normally open valve that is closed when a voltage is supplied in response to a command signal from a control unit (ECU) 20 and is open when no voltage is supplied. As a result, even if some abnormality occurs in the steering system and the power supply is shut down, the first cylinder chamber 2a and the second cylinder chamber 2b can be brought into communication with each other. Steering can be ensured.

  The check valves 5 and 5 are closed when hydraulic pressure is generated by the bidirectional pump 3, and are released when negative pressure is generated. The reservoir tank T supplies oil to the bidirectional pump 3 and stores drained oil. Further, the steering shaft 1 is provided with a torque sensor TS for detecting the steering torque of the driver.

  The control unit (ECU) includes a steering torque signal from the torque sensor TS, an ignition signal from the ignition switch (not shown), an engine speed signal from the engine speed sensor (not shown), and a vehicle speed sensor (not shown). The vehicle speed signal is input. Based on these input signals, command signals are output to the electric motor M, the fail safe valve 4 and the warning lamp WL of the bidirectional pump 3.

FIG. 2 is a diagram illustrating a configuration in the control unit (ECU) of the first embodiment.
When a steering torque signal is generated from the torque sensor TS by the driver's operation of the steering wheel SW and inputted to the control unit (ECU) 20, a motor rotation command torque is calculated from the steering torque signal.

  From the magnetic pole position calculated from the motor rotation sensor 206 and the motor rotation command torque, the microcomputer 200 calculates target current values for the u-phase, v-phase, and w-phase, and outputs PWM signals to the drive elements 207 to 212. The electric motor M is driven. As the motor rotation sensor 206, a sensor using a rotary encoder, a Hall element or the like can be considered. Further, the driving elements 207 to 212 for each phase may be, for example, MOS-FETs as switching elements driven by PWM control, but are not particularly limited.

  Next, feedback control is performed so that the current values detected by the current sensors (corresponding to current detection means in claims) 203 to 205 are matched with the target current value of each phase.

  When the current values detected by the current sensors 203 to 205 are normal, the normally open type fail-safe valve 4 in the bypass oil passage 6 is closed by an energization command from the control unit (ECU) 20. At this time, when the electric motor M is driven and oil is pumped out by the bidirectional pump 3, the pressure in the pressure chambers on the side requiring assistance among the pressure chambers 2a and 2b increases. Thereby, an assist force can be obtained.

  When it is detected that any one of the current sensors 203 to 205 provided in each of the three phases has failed, the current value of the phase in which the current sensor is broken is estimated from the values of the remaining two-phase current sensors, Torque control is continued by driving the motor based on the obtained current value. At this time, the driver is notified of the failure detection by the warning lamp WL.

  The current sensors 201 and 202 detect when the upstream and downstream drive elements of the u-phase, v-phase, and w-phase are turned on simultaneously and a short-circuit current flows. You may provide in both, or you may provide in either upstream or downstream.

FIG. 3 is a flowchart showing the contents of current control according to the first embodiment.
In step 301, the target motor torque is calculated, and the process proceeds to step 302.

  In step 302, the target motor current is calculated, and the process proceeds to step 303.

In step 303, the target motor current of each phase of u phase, v phase, and w phase is calculated from the magnetic pole position and each phase current I _*, and the process proceeds to step 304.

  In step 304, the PWM output current is calculated, and the process proceeds to step 305.

  In step 305, PWM output is performed, and this control flow ends.

FIG. 4 is a flowchart showing the contents of current calculation in the u phase of the first embodiment. The same calculation is performed for the v phase and the w phase.
In step 401, it is confirmed whether or not the current sensor is normal. If there is no abnormality, the process proceeds to step 402, and if there is an abnormality, the process proceeds to step 403. In addition, for current sensor abnormality determination, the current sensor monitor value is output when the drive signal is not output, and when normal, the output is set within a certain range and out of that range. If it is determined to be abnormal. As will be described later, the motor drive is not affected by monitoring the current value that does not hold the relational expression of the current value of each phase.

If it is determined that the current sensor is normal, the u-phase current value I _u is set to the value I _umon monitored by the current sensor 203 in step 402.

If it is determined that the u-phase current value is abnormal, in step 403, the u-phase current value is calculated from the relational expression I _u + I _v + I _w = 0 of the three-phase motor by I _u = − ( I _v + I _w )

  When a current sensor is provided for each phase as in the first embodiment, even if one current sensor fails, it can be estimated using another current sensor. At this time, the current sensor monitor value is output so that the motor M is not driven in the state where the drive signal is not output, and an abnormality is determined. As a result, it is possible to set a current value used for motor drive control at a stage prior to outputting a drive signal, and stable motor drive control can be achieved. In particular, in motor drive control where responsiveness is required, it works effectively.

Hereinafter, the operation and effect of the first embodiment will be described based on comparison with the conventional example. FIG. 5A is a diagram illustrating a conventional current control configuration.
Current sensors as current detecting means are provided in two phases, the current value of the remaining one phase is estimated from the two current sensor values, and torque control is performed by motor driving based on the obtained current values. For this reason, when one current sensor fails, it is impossible to estimate the current value of the phase in which the current sensor is not provided, and thus torque control cannot be continued by driving the motor based on the current value. Further, when only two phases of current sensors are provided, the resistance value varies in each phase. Therefore, it is necessary to use a highly sensitive non-contact type expensive sensor, which leads to an increase in cost.

FIG. 5B is a diagram illustrating a current control configuration according to the first embodiment.
In the first embodiment, since current sensors as current detection means are provided for all three phases, even if any one phase current sensor fails, the currents are detected using the values of the remaining two-phase current sensors. The current value of the phase in which the sensor has failed can be estimated, and torque control can be continued by driving the motor based on the obtained current value.

  When an inexpensive shunt resistance type current sensor is used, the current value becomes smaller than the actual current value due to the shunt resistance. For example, when a shunt resistance type current sensor is applied to only two phases as in the conventional example, there is a possibility that the balance of the current value between the phase to which the current sensor is applied and the phase to which the current sensor is not applied is deteriorated.

  On the other hand, when shunt resistance type current sensors are used for all three phases as in the first embodiment, the current values of all three phases are similarly reduced, so that the current values of the three phases can be balanced. . Even if a failure occurs in the current sensor, the resistance value does not change. Therefore, an inexpensive shunt resistance type current sensor can be applied to achieve stable current detection while reducing costs.

  Further, technical ideas other than the claims that can be grasped from the respective embodiments will be described below together with the effects thereof.

(A) In the drive control device for a DC non-commutator motor according to claim 1,
All phases of the DC non-commutator motor are provided with shunt resistors as current detection means for each phase, and the current value flowing through each phase is obtained from the voltage across the shunt resistor and the resistance value of the shunt resistor. A DC non-commutator motor drive control device, wherein torque control is performed by a DC non-commutator motor.

  Since current detection means are provided in all phases and the resistance values of all phases are the same, it is possible to obtain an accurate value of the current value flowing in each phase, and the accuracy of torque control by the motor is improved. . In addition, an inexpensive shunt resistance type current sensor can be used, and the cost can be reduced.

(B) In the drive control device for a DC non-commutator motor according to claim 1,
The abnormality detection means outputs a current monitor value when no motor drive signal is output, and detects an abnormality of the current detection means when the current value detected by the current detection means is outside a predetermined range. A drive control device for a DC non-commutator motor, characterized in that it is a means.

  The current monitor value that is output when the drive signal is not output is set so that when the current monitor value is normal, the output is within a predetermined range. It is possible to detect an abnormality in the current detection means by a simple method such as determining “I”. Further, the current sensor monitor value is output so that the motor M is not driven in a state where the drive signal is not output, and an abnormality is determined. As a result, it is possible to set a current value used for motor drive control at a stage prior to outputting a drive signal, and stable motor drive control can be achieved. In particular, the motor drive control that requires responsiveness can work effectively.

It is a whole block diagram of the drive control apparatus of the direct current non-commutator motor in a present Example. FIG. 3 is a diagram illustrating a configuration inside a control unit ECU according to the first embodiment. 3 is a flowchart illustrating the contents of current control according to the first embodiment. 3 is a flowchart showing the contents of current calculation in the u phase of the first embodiment. It is a figure showing the electric current control structure of a prior art example and Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering shaft 2 Power steering mechanism 21 Power cylinder 2a 1st cylinder chamber 2b 2nd cylinder chamber 3 Bidirectional pump 4 Fail safe valve 5 Check valve 20 Control unit (ECU)
200 Microcomputer 201, 202 Current sensor 203 u-phase current sensor 204 v-phase current sensor 205 w-phase current sensor 206 motor rotation sensor 207 u-phase upstream drive element 208 u-phase downstream drive element 209 v-phase upstream drive element 210 v-phase Downstream drive element 211 w-phase upstream drive element 212 w-phase downstream drive element SW Steering wheel TS Torque sensor L Rack P Pinion M Electric motor T Reservoir tank WL Warning lamp

Claims (1)

In a drive control device for a DC non-commutator motor,
Current detection means for detecting the current of each phase;
An abnormality detection means for detecting an abnormality of the current detection means;
Current value estimation means for estimating a current value of a phase in which an abnormality is detected based on a current value of a phase other than the phase in which an abnormality is detected by the abnormality detection means;
A drive control device for a DC commutator motor, comprising:

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