JP6730488B2 - Control device and drive device for three-phase synchronous motor, and electric power steering device - Google Patents

Description

The present invention relates to a control device and a drive device for a three-phase synchronous motor, and an electric power steering device.

Compact and highly efficient three-phase synchronous motors are widely used in various fields such as industry, home appliances, and automobiles. However, in a three-phase synchronous motor, generally, the rotational position of a rotor provided with a magnet is detected by a magnetic detection element such as a Hall IC, and based on the detection result, the armature coils on the stator side are sequentially excited to sequentially rotate the rotor. Is rotating. In addition, by using a resolver, an encoder, a GMR sensor, or the like, which is a precise rotational position detector, driving with a sine wave current can be realized, and there are some that reduce vibration and noise such as torque ripple.

However, if the rotational position detector fails, the three-phase synchronous motor cannot immediately rotate. This is also the case when a resolver, an encoder, or a GMR sensor is used as the rotational position detector. As described above, the failure of the rotational position detector causes malfunction or abnormal operation in the drive device of the three-phase synchronous motor such as the electric power steering, and therefore improvement has been demanded.

The invention described in Patent Document 1 has a rotational position estimation means for estimating the position from the voltage and current of the three-phase synchronous motor in addition to the rotational position detector when the rotational position detector fails. By using this rotational position estimating means as a substitute for the output of the rotational position detector, the three-phase synchronous motor can be stably driven even when the rotational position detector fails.

JP, 2010-22196, A

When the rotational position estimating means is used instead of the rotational position detector when the rotational position detector fails as in Patent Document 1, the three-phase synchronous motor can be continuously driven. However, a difference occurs between the actual rotor position and the estimated rotor position, and the output of the three-phase synchronous motor decreases. Therefore, it is possible to use two rotary position detectors such as a resolver, an encoder, and a GMR sensor, which have high rotational position detection accuracy, so that when one of the rotary position detectors fails, the other rotary position detector is used. To be However, with this method, it is not possible to determine which of the two rotational position detectors is defective, so it is necessary to use three or more rotational position detectors, and the increase in the cost of the rotational position detectors becomes a problem. It was

An object of the present invention is to provide a control device, a drive device, and an electric power steering device for a three-phase synchronous motor that improves the reliability of the rotational position detector of a three-phase synchronous motor without increasing the cost of the rotational position detector. To provide.

A control device for a three-phase synchronous motor according to the present invention is based on signals from a first rotational position detector and a second rotational position detector that detect a rotor position of the three-phase synchronous motor. Which controls the rotor position based on any one of a neutral point potential of the three-phase synchronous motor , a virtual neutral point potential , a magnetic saturation electromotive voltage, and a salient pole of the three-phase synchronous motor. Rotating position estimating means, the rotating position estimating means has first rotating position estimating means and second rotating position estimating means, and outputs the output signal of the first rotating position detector and the second rotating position detector. When the output signal of the rotational position detector is different, the output signal of the first rotational position detector and the second rotational position detection are based on the rotor position calculated by the first rotational position estimating means. If any one of the output signals of the detector is selected and the first rotational position detector and the second rotational position detector are abnormal, the output of the first rotational position estimation means and the second rotational position estimation means are selected. When the outputs of the rotational position estimating means are substantially the same, the output of the first rotational position estimating means is used, and the output of the first rotational position estimating means and the output of the second rotational position estimating means are used. Is different, the output of the second rotational position estimating means is used to control the three-phase synchronous motor.

A drive device for a three-phase synchronous motor according to the present invention includes a control device for a three-phase synchronous motor according to the present invention and a three-phase synchronous motor controlled by the control device.

An electric power steering apparatus according to the present invention steers a tire with a control device for a three-phase synchronous motor according to the present invention, a three-phase synchronous motor controlled by the control device, and an output torque of the three-phase synchronous motor. And a steering mechanism capable of performing the operation.

According to the control device and the drive device for the three-phase synchronous motor and the electric power steering device according to the preferred embodiment of the present invention, the rotational position estimating means determines which of the two rotational position detectors is defective. To do. By doing so, it is possible to operate without reducing the output of the three-phase synchronous motor due to the failure of one of the two rotational position detectors.

Other objects and characteristics of the present invention will be clarified in the embodiments described below.

It is a block diagram of the drive device of the three-phase synchronous motor according to the first embodiment. This is the process of the detection position determination means 1. It is a block diagram showing a position estimating means 2 based on a neutral point potential. It is a block diagram of the drive device of the three-phase synchronous motor which used the shunt current detection part 36 for current detection. It is a block diagram of the electric power steering apparatus which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the drive device of the three-phase synchronous motor concerning 2nd Embodiment. This is the process of the detection position selection means 9.

Hereinafter, an embodiment of a power converter according to the present invention will be described with reference to the drawings. In each figure, the same elements are designated by the same reference numerals, and overlapping description will be omitted.

(First embodiment)
A first embodiment of a drive device for a three-phase synchronous motor according to the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 shows the configuration of a drive device 6 for a three-phase synchronous motor. The drive device 6 for the three-phase synchronous motor is intended to drive the three-phase synchronous motor 4. The drive device 6 for a three-phase synchronous motor according to the present embodiment is configured to include a detected position determination means 1, a rotational position estimation means 2, a power converter 3, a three-phase synchronous motor 4 to be driven, and a controller 5. It

The drive device according to the present embodiment is characterized in that a failure (abnormality) of the first rotational position detector 41 and the second rotational position detector 42 is determined by the rotational position estimating means 2 and the rotational position is correctly output. Using the detector to drive the three-phase synchronous motor 4.

As shown in FIG. 1, the detected position determination means 1 receives the output θ1 of the first rotational position detector 41, the output θ2 of the second rotational position detector 42, and the output θ3 of the rotational position estimation means 2. It Then, the detected position determination means 1 outputs the rotational position θ.

FIG. 2 is a diagram showing a processing flow of the detected position determination means 1. The detection position determining means 1 first determines whether or not the outputs θ1 and θ2 of the two rotational position detectors substantially match. If the outputs substantially match, θ1 is used. Although θ1 is used in this embodiment, θ2 may be used.

When θ1 and θ2 are different, it can be determined that one of the rotational position detector 41 and the rotational position detector 42 is out of order. However, it is not possible to determine which one of the rotational position detector 41 and the rotational position detector 42 is out of order.

Therefore, the output θ3 of the rotational position estimating means 2 is used to determine which is the correct output. First, it is determined whether θ1 and θ3 substantially match. When the outputs substantially match, θ1 is determined to be the output from the normal rotational position detector, and θ1 is used. On the other hand, when the outputs of θ1 and θ3 are different, it is determined whether θ2 and θ3 are substantially the same. When the outputs substantially match, θ2 is determined to be the output from the normal rotational position detector, and θ2 is used. If θ2 and θ3 are different, θ3 is used.

With respect to θ1, θ2, and θ3 to be compared, three positions are corrected by correcting the detection timing of the rotational position detector, and comparison is performed at the same time. By doing so, the rotational position at the same timing can be detected appropriately, so that it is possible to prevent erroneous detection of a failure of the rotational position detector when comparing the rotational positions.

By configuring the detection position determining means 1 as shown in FIG. 2, even if the first rotation position detector 41 or the second rotation position detector 42 fails, a normal rotation position detector can be provided. It is possible to select and output the torque of the three-phase synchronous motor similar to that in the normal state. Further, even if both the first rotational position detector 41 and the second rotational position detector 42 fail, the rotational position estimating means 2 is used to maintain the drive of the three-phase synchronous motor. It becomes possible to secure redundancy.

FIG. 3 shows the configuration of the rotational position estimating means 2. The rotational position estimation means 2 estimates the rotational position estimated value θ3 from the virtual neutral point Vn. At this time, there is a known technique for estimating the rotational position estimated value θ3 from the detected virtual neutral point Vn, but one of them is introduced. The rotational position estimating means 2 includes a neutral point potential detecting unit 21, a sample/hold unit 22, and a rotational position estimating unit 23.

The neutral point potential detector 21 detects the virtual neutral point potential Vn0 according to the pulse width modulation signal output from the pulse width modulation signal output means 33. At this time, there is a known technique for detecting the virtual neutral point potential Vn0 from the three-phase synchronous motor 4, and since it is not a main part of the present invention, description thereof will be omitted.

The sample/hold unit 22 is an AD converter for sampling and quantizing (sampling) the analog signal output of the neutral point potential detecting unit 21. The sample/hold unit 22 samples this Vn0 in synchronization with the pulse width modulation signal output from the pulse width modulation signal output means 33. The sample/hold unit 22 outputs the sampled result (Vn0h) to the rotational position estimation unit 23 as a digital signal.

The rotational position estimation unit 23 calculates an estimated value θ3 of the rotational position of the three-phase synchronous motor 4 based on the neutral point potential sampled by the sample/hold unit 22. This estimation result is output as the output θ3 of the rotational position estimating means 2.

The characteristic of the rotational position estimating means 2 is that torque can be produced when the rotational speed of the three-phase synchronous motor is zero. As the rotational position estimating means 2, the means for estimating the rotational position estimated value θ3 from the virtual neutral point Vn has been introduced in the present embodiment. However, the method based on the magnetic saturation electromotive voltage, the difference in salient polarity of the three-phase synchronous motor 4 is introduced. Is known, and any one of them may be used. Further, instead of the virtual neutral point, a three-phase winding connection point (neutral point) may be directly drawn and detected. Even when the three-phase synchronous motor 4 is stopped, the rotational position estimating means 2 can detect the rotational position and output torque.

Further, by comparing the output θ3 of the rotational position estimating means 2 with θ1 and θ2, the abnormality of the first rotational position detector 41 and the second rotational position detector 42 is detected. Thus, the normal output θ3 of the rotational position estimating means 2 can be used to start the three-phase synchronous motor 4 from the stopped state.

It returns to FIG. 1 and demonstrates. The control unit 5 generates a pulse width modulation signal from the output θ of the detected position determination means 1. The power converter 3 applies a voltage to the three-phase synchronous motor 4 based on the pulse width modulation signal output from the control unit 5. The power converter 3 includes a DC power supply 31, a power conversion circuit 32, a pulse width modulation signal output means 33, a virtual neutral point potential detection circuit 34, a three-phase current detector 35, and a shunt current detector 36.

The DC power supply 31 is a DC power supply that supplies a current to the power conversion circuit 32. The power conversion circuit 32 is a power conversion circuit including six switching elements Sup to Swn. The pulse width modulation signal output means 33 is a driver for inputting the pulse width modulation signal output from the control unit 2 to the power converter 32. The neutral point potential detection unit 34 detects a virtual neutral point Vn used in the rotational position estimating means. Instead of the virtual neutral point Vn, the neutral point potential of the three-phase synchronous motor 4 may be directly detected. The three-phase current detector 35 is a current detector that detects three-phase currents Iu, Iv, and Iw flowing through the three-phase synchronous motor 4. For the current detection of the three-phase synchronous motor 4, it is desirable to directly detect the three-phase current supplied from the power conversion circuit 32 to the three-phase synchronous motor 4 like the current detector 35, but as shown in FIG. The currents Iu, Iv, and Iw that reproduce the three-phase current by detecting the direct current Idc flowing through the resistor 36 may be used. There is a known technique for reproducing the three-phase currents Iu, Iv, and Iw from the DC current Idc, and the description thereof is omitted because it is not a main part of the present invention.

According to the drive device for a three-phase synchronous motor according to the present embodiment described above, the rotational position estimating means determines which of the two rotational position detectors is defective. By doing so, even if one of the two rotational position detectors fails, the operation can be continued without reducing the output of the three-phase synchronous motor. Since the rotational position estimating means as shown in the present embodiment can be realized without adding hardware such as a rotational position detector, the three-phase synchronous motor can be realized without increasing the cost of the rotational position detector. The reliability of the rotational position detector can be improved.

(Second embodiment)
A second embodiment of the electric power steering according to the present invention will be described with reference to FIGS. 5 to 7.

FIG. 5 shows the configuration of the electric power steering device 8. When the driver operates the steering wheel 81, the torque sensor 82 detects the rotational torque of the steering wheel 81. The torque detected by the torque sensor 82 is input to the drive device 6, and the three-phase synchronous motor 4 outputs the torque based on a command corresponding to the torque. The output torque of the three-phase synchronous motor 4 assists the steering force via the steering assist mechanism 83 and is output to the steering mechanism 84. Then, the tire 85 is steered by the steering mechanism 84.

FIG. 6 shows the configuration of the drive device 6 for the three-phase synchronous motor according to this embodiment. In this embodiment, the rotation position estimating means includes a first rotation position estimating means 2 and a second rotation position estimating means 2. The difference from the first embodiment is that a second rotational position estimating means 7 is provided.

The first rotation position estimating means 2 and the second rotation position estimating means 7 are provided for the method based on the virtual neutral point Vn introduced in the first embodiment, the method based on the magnetic saturation electromotive force, and the three-phase synchronous motor. Any two of the four saliency methods may be used. The feature of these three rotational position estimating means is that even when the rotational speed of the three-phase synchronous motor is 0, the drive control of the three-phase synchronous motor is possible and the torque can be output. In the electric power steering apparatus having such a rotational position estimating means, torque can be output even when the rotational speed of the three-phase synchronous motor is 0. Therefore, for example, even when the tire of the vehicle runs on a step, the driver's steering wheel Can be assisted.

From the above characteristics, the first rotational position estimation means 2 can estimate the rotational position even when the three-phase synchronous motor 4 is stopped. Therefore, by comparing θ3 with θ1 and θ2, the first rotational position detection can be performed. The abnormality of the device 41 and the second rotational position detector 42 can be detected. Further, even when the speed of the vehicle is equal to or lower than the predetermined speed and the three-phase synchronous motor 4 is stopped, the first rotational position estimating means 2 can estimate the rotational position. Therefore, by comparing θ3 with θ1 and θ2. , The abnormality of the first rotational position detector 41 and the second rotational position detector 42 can be detected.

Even when the rotation speed of the three-phase synchronous motor 4 is 0 and the speed of the vehicle is equal to or lower than a predetermined speed, the output θ3 of the first rotation position estimation means 2 is compared with θ1 and θ2 to detect the first rotation position. By detecting an abnormality in the device 41 and the second rotational position detector 42, the normal output θ3 of the first rotational position estimating means 2 can be used to continuously drive the three-phase synchronous motor 4 and assist the steering force. ..

FIG. 7 shows the processing of the detection position selecting means 9, which is a feature of the second embodiment. The detection position selection means 9 inputs θ1 to θ4 which are outputs of the first rotation position detector 41, the second rotation position detector 42, the first rotation position estimation means 2 and the second rotation position estimation means 7. Then, the estimated rotational position value θ is output. The detection position selection means 9 first determines whether or not the outputs θ1 and θ2 of the two rotational position detectors substantially match. If the outputs substantially match, θ1 is used. However, when θ1 and θ2 are different, it cannot be determined which rotational position detector is out of order. Therefore, the output θ3 of the rotational position estimating means 2 is used to determine which is the correct output. Next, it is determined whether or not θ1 and θ3 substantially match, and when the outputs substantially match, θ1 is used. If the outputs of θ1 and θ3 are different, it is determined whether θ2 and θ3 are substantially the same. If the outputs substantially match, θ2 is used. When θ2 and θ3 are different, it is determined whether θ3 and θ4 are substantially the same. If the outputs substantially match, θ3 is used. If the outputs of θ3 and θ4 are different, θ4 is used.

By configuring the detection position selecting means 9 as shown in FIG. 7, even if either the first rotation position detector 41 or the second rotation position detector 42 fails, the normal position is detected. Rotational position detectors can be used. As a result, the steering force can be assisted in the electric power steering as usual.

When both the first rotational position detector 41 and the second rotational position detector 42 are out of order, the steering force can be assisted by using the first rotational position estimation means 2. In addition, even when the output of the first rotational position estimating means 2 is abnormal, the second rotational position estimating means 7 can be used, so that a quadruple redundant system can be provided at low cost.

When the output θ1 of the first rotational position detector 41 and the output θ2 of the second rotational position detector 41 both become abnormal and malfunction, the detected position selecting means 9 includes the first rotational position estimating means 2 and the first rotational position estimating means 2. .Theta.3 and .theta.4 which are the outputs of the rotational position estimating means 7 of No. 2 are used. At this time, the driver is notified of the failure, and the output of the three-phase synchronous motor is gradually reduced. By doing so, even if the electric power steering system fails, the driver can stop the vehicle safely.

With respect to θ1, θ2, θ3, and θ4 to be compared, three positions are corrected by correcting the detection timing of the rotational position detector, and comparison is performed at the same time. By doing so, it is possible to appropriately detect the rotational position at the same timing, so that it is possible to prevent erroneous detection when comparing the rotational positions.

1: Detected position determination means 2: Rotational position estimation means (first rotational position estimation means)
21: neutral point potential detection unit 22: sample/hold unit 23: rotational position estimation unit 3: power converter 31: DC power supply 32: power conversion circuit 33: pulse width modulation signal output means 34: virtual neutral point potential detection Circuit 35: Three-phase current detector 36: Shunt current detector 4: Three-phase synchronous motor 41: First rotational position detector 42: Second rotational position detector 5: Controller 6: Driving of three-phase synchronous motor Device 7: Second rotational position estimating means 8: Electric power steering device 81: Steering wheel 82: Torque sensor 83: Steering assist mechanism 84: Steering mechanism 85: Tire 9: Detection position selecting means

Claims (5)

A control device for controlling the three-phase synchronous motor based on signals from a first rotational position detector and a second rotational position detector that detect a rotor position of the three-phase synchronous motor,
A neutral position potential of the three-phase synchronous motor , a virtual neutral point potential , a magnetic saturation electromotive force, a rotational position estimation means for calculating the rotor position based on any of the salient poles of the three-phase synchronous motor ,
The rotation position estimating means has a first rotation position estimating means and a second rotation position estimating means,
When the output signal of the first rotational position detector and the output signal of the second rotational position detector are different, the first rotational position estimating means calculates the first rotational position based on the rotor position calculated by the first rotational position estimating means. Selecting one of the output signal of the rotational position detector and the output signal of the second rotational position detector,
When the first rotational position detector and the second rotational position detector are abnormal,
When the output of the first rotational position estimating means and the output of the second rotational position estimating means are substantially the same, the output of the first rotational position estimating means is used,
When the output of the first rotational position estimating means and the output of the second rotational position estimating means are different, the output of the second rotational position estimating means is used,
A control device for a three-phase synchronous motor, which controls the three-phase synchronous motor. A control device for a three-phase synchronous motor according to claim 1,
When the output signal of the first rotational position detector and the output signal of the second rotational position detector substantially match, the three-phase synchronous motor is based on the output signal of the first rotational position detector. A control device for a three-phase synchronous motor, characterized by controlling the. A control device for a three-phase synchronous motor according to claim 1 or 2, wherein
When an abnormality is detected in either the first rotational position detector or the second rotational position detector, both the first rotational position detector and the second rotational position detector are normal. so as to output the same torque as the case is, the control device of the three-phase synchronous motor, characterized by controlling the three-phase synchronous motor. A control device for a three-phase synchronous motor according to any one of claims 1 to 3,
And a three-phase synchronous motor controlled by the control device. A control device for a three-phase synchronous motor according to any one of claims 1 to 3,
A three-phase synchronous motor controlled by the control device,
An electric power steering apparatus comprising: a steering mechanism capable of steering a tire by the output torque of the three-phase synchronous motor.

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