JP2013253796A - Resolver excitation circuit and control device of electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resolver excitation circuit capable of supplying a correct excitation signal to a resolver, and a control device of an electric power steering device including a position detection device using the resolver excitation circuit.SOLUTION: Three PWM signal generating circuits 221 to 223, three XOR circuits 224 to 226, and three rising edge detection circuits 227 to 229 perform abnormality monitoring of the PWM signal generating circuits 221 to 223. A PWM signal switching circuit 232 selects any one of the PWM signal generating circuits 221 to 223 on the basis of an abnormality monitoring result, and generates an excitation signal supplied to a resolver on the basis of a PWM signal from the selected PWM signal generating circuit.

Description

  The present invention relates to a resolver excitation circuit for exciting a resolver used for detecting a position such as a rotation angle, and a control device for an electric power steering apparatus using the resolver excitation circuit.

As a position detection device using a conventional resolver, there is a technique described in Patent Document 1, for example. This technique includes an excitation signal circuit that generates a sinusoidal excitation signal, and excites a resolver by an excitation signal output from the excitation signal circuit. However, when only one excitation signal circuit is provided as described above, if an abnormality occurs in the excitation signal circuit, a correct excitation signal is not output, and the resolver cannot be excited.
Thus, for example, there is a technique described in Patent Document 2 as a plurality of circuits (PWM signal generation circuit) that generate a PWM signal that is a source of an excitation signal. In this technique, two PWM signal generation circuits having different PWM signal generation methods are provided, and an excitation signal is generated based on a PWM signal generated by any one of them.

JP 2010-2117006 A JP 2008-216130 A

However, the technique described in Patent Document 2 does not have an abnormality monitoring function and switching function of the PWM signal generation circuit. Therefore, when an abnormality occurs in the effective PWM signal generation circuit, it is not possible to perform a treatment such as detecting the abnormality and switching to a normal PWM signal generation circuit. Therefore, a correct excitation signal cannot be output and the resolver cannot be excited.
Accordingly, an object of the present invention is to provide a resolver excitation circuit that can supply a correct excitation signal to a resolver, and a control device for an electric power steering device using the resolver excitation circuit.

  In order to solve the above problems, a resolver excitation circuit according to the present invention is a resolver excitation circuit that supplies an excitation signal to a resolver, and includes three independent PWM signal generation circuits that respectively generate PWM signals having the same waveform; Three XOR circuits that input PWM signals from two of the three PWM signal generation circuits and detect mismatches between the two PWM signals for all combinations, and output signals of the three XOR circuits PWM signal that generates a PWM signal that is the source of the excitation signal out of the three PWM signal generation circuits based on the output of the edge detection circuit and three edge detection circuits that respectively detect the presence or absence of rising edges And a PWM signal switching circuit for selecting the generation circuit.

  In this way, when an abnormality occurs in the PWM signal generation circuit, the PWM signal generated by each PWM signal generation circuit is shifted in the rising timing, and the PWM signal is output depending on the presence or absence of the rising edge of the output signal of the XOR circuit. Monitor the signal generation circuit for abnormalities. Therefore, a combination of three PWM signal generation circuits and a simple logic circuit (XOR circuit) can identify a circuit in which an abnormality has occurred among the three PWM signal generation circuits. Furthermore, since the valid PWM signal generation circuit can be switched based on the abnormality monitoring result of the PWM signal generation circuit, the continuity of correct excitation signal output can be improved.

In the above, the PWM signal switching circuit matches the output when the output of the edge detection circuit is abnormal in one of the three PWM signals generated by the PWM signal generation circuit. When the PWM signal generation circuit is selected, it is composed of three changeover switches so that one of the remaining two normal PWM signals becomes the PWM signal that is the source of the excitation signal. It is characterized by.
Thus, when an abnormality occurs in one of the three PWM signals, an excitation signal can be generated based on the normal PWM signal and supplied to the resolver. In this way, a backup function in the event of an abnormality can be realized with a relatively simple circuit configuration in which only three changeover switches are provided.

  Further, in the above, further comprising: an AND circuit that inputs the outputs of the three edge detection circuits; and an output stop switch that turns on and off the output of the PWM signal switching circuit based on the outputs of the AND circuit. The stop switch is configured such that the output of the AND circuit matches the output when the output of the edge detection circuit is abnormal in two or more of the three PWM signals generated by the PWM signal generation circuit. The PWM signal switching circuit is configured to stop the output.

  As described above, when abnormality occurs in two of the three PWM signals, the normal PWM signal cannot be specified, and the output of the PWM signal generation circuit is stopped, and the system is set to the safe side. Can be migrated. That is, a fail-safe function can be realized by combining a simple logic circuit (AND circuit) and one output stop switch. Therefore, it is possible to prevent the excitation signal from being generated based on the PWM signal in which an abnormality has occurred.

The control device for the electric power steering apparatus according to the present invention includes position detection means for detecting a rotational position of a motor that assists a steering system of the vehicle, and is based on steering torque and position information from the position detection means. A control device for an electric power steering device for driving and controlling a motor, wherein the position detection means includes a resolver and the resolver excitation circuit according to any one of the above that supplies an excitation signal to the resolver. It is said.
Thus, since the resolver excitation circuit having the abnormality monitoring function of the PWM signal generation circuit and the backup function at the time of abnormality occurrence is used, the rotational position of the motor can be appropriately detected by the position detection means. Therefore, appropriate steering assist control can be performed based on the rotational position of the motor detected by the position detecting means.

In the resolver excitation circuit according to the present invention, an abnormality monitoring function of the PWM signal generation circuit and a backup function when an abnormality occurs can be realized by a combination of three PWM signal generation circuits and a simple logic circuit. Therefore, the continuity of normal excitation signal output can be improved.
In addition, the position detection means using such a resolver excitation circuit can detect an appropriate angle by normal resolver excitation, so that the reliability of the control device of the electric power steering apparatus can be improved.

1 is an overall configuration diagram of an electric power steering apparatus according to an embodiment. It is a circuit diagram of a resolver excitation circuit. It is a timing chart explaining operation at the time of normal. It is a timing chart explaining operation | movement at the time of abnormality occurrence.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of an electric power steering apparatus according to the present embodiment.
In the figure, reference numeral 1 denotes a steering wheel, and a column shaft 2 of the steering wheel 1 is connected to a tie rod 6 of a steering wheel via a reduction gear 3, universal joints 4A and 4B, and a pinion rack mechanism 5.

The column shaft 2 is provided with a torque sensor 10 that detects the steering torque of the steering wheel 1, and a motor 20 that assists the steering force of the steering wheel 1 is connected to the column shaft 2 via the reduction gear 3. .
The motor 20 is provided with a resolver 21 as a position detection sensor (position detection means) that detects the rotational position of the motor 20. The resolver 21 is supplied with an excitation signal from a resolver excitation circuit incorporated in the control unit 30. The configuration of the resolver excitation circuit will be described in detail later.

The control unit 30 operates when power is supplied from a vehicle-mounted battery 14 (for example, the rated voltage is 12V). The negative electrode of the battery 14 is grounded, and the positive electrode thereof is connected to the control unit 30 via the ignition key 11 for starting the engine, and is directly connected to the control unit 30 without passing through the ignition key 11.
As described above, the control unit 30 is supplied with electric power from the battery 14 and also receives the ignition key signal IGN via the ignition key 11.

  Further, the control unit 30 inputs the steering torque Ts detected by the torque sensor 10, the vehicle speed V detected by the vehicle speed sensor 12, and the rotational position of the motor 20 detected by the resolver 21, and based on these, steering assist Command value (current command value) I is calculated. Based on the calculated steering assist command value I, the current supplied to the motor 20 is controlled. By controlling the drive of the motor 20 in this way, a steering assist force that assists the driver's steering is applied to the steering system.

Next, the configuration of the resolver excitation circuit will be specifically described.
FIG. 2 is a circuit diagram of a resolver excitation circuit. The resolver excitation circuit is formed inside a microcontroller (MCU) and generates a PWM signal P ′ that is the source of the excitation signal. The resolver excitation circuit filters the PWM signal P ′ generated by the PWM signal output circuit 22. And a secondary low-pass filter (second-order LPF) 23 for outputting a sinusoidal excitation signal.

The PWM signal output circuit 22 includes three PWM signal generation circuits 221, 222, and 223. The PWM signal generation circuits 221 to 223 are configured to generate the PWM signals P1 to P3 having the same waveform independently and using different generation methods in order to avoid a failure due to a common factor.
The PWM signal P1 generated by the PWM signal generation circuit 221 is input to the XOR circuit 224 and the XOR circuit 226. The PWM signal P2 generated by the PWM signal generation circuit 222 is input to the XOR circuit 224 and the XOR circuit 225. Further, the PWM signal P3 generated by the PWM signal generation circuit 223 is input to the XOR circuit 225 and the XOR circuit 226.

  That is, processing for detecting mismatch by inputting two PWM signals among the three PWM signals P1 to P3 by the three XOR circuits 224 to 226 is performed for all combinations. The output signals of the three XOR circuits 224 to 226 are provided corresponding to the three XOR circuits 224 to 226, respectively, and a rising edge detection circuit (simply an edge detection circuit) that detects the presence or absence of the rising edge of the output signal. (Also called).

  The output signal of the XOR circuit 224 is input to the rising edge detection circuit 227. When the rising edge detection circuit 227 detects the rising edge of the output signal from the XOR circuit 224, the edge detection flag flg1 is switched from Low to High. Here, when the rising edge detection circuit 227 detects a rising edge once and switches the edge detection flag flg1 from Low to High, it has a function of maintaining the state thereafter.

The output signal of the XOR circuit 225 is input to the rising edge detection circuit 228, and the output signal of the XOR circuit 226 is input to the rising edge detection circuit 229. The rising edge detection circuits 228 and 229 have the same configuration as the rising edge detection circuit 227, and output edge detection flags flg2 and flg3, respectively.
The edge detection flags flg1 and flg2 are input to the AND circuit 230. The output signal of the AND circuit 230 and the edge detection flag flg3 are input to the AND circuit 231. The output signal of the AND circuit 231 is input to a switch SW4 described later as a PWM output stop signal S1. That is, the output signal (PWM output stop signal S1) of the AND circuit 231 is a signal that becomes High when all the edge detection flags flg1 to flg3 are High.

The PWM signals P1 to P3 generated by the PWM signal generation circuits 221 to 223 and the edge detection flags flg1 to flg3 are input to the PWM switching circuit 232, respectively. The PWM switching circuit 232 includes three switches SW1 to SW3 (switching switches).
When the edge detection flag flg1 is Low, the switch SW1 selects the PWM signal P1 as shown by the solid line, and when the edge detection flag flg1 becomes High, the switch SW1 switches to the state shown by the broken line and selects the PWM signal P2.

When the edge detection flag flg3 is Low, the switch SW2 selects the PWM signal P3 as shown by the solid line, and when the output signal of the edge detection flag flg3 becomes High, the switch SW2 switches to the state shown by the broken line and selects the PWM signal P1. To do.
Further, when the edge detection flag flg2 is Low, the switch SW3 selects the PWM signal selected by the switch SW1 as indicated by the solid line, and when the edge detection flag flg2 becomes High, the switch SW3 switches to the state indicated by the broken line. Select the PWM signal selected in. The output signal of the switch SW3 becomes the output signal of the PWM signal switching circuit 232.

In this way, the PWM signal switching circuit 232 selects and outputs one of the three PWM signals P1 to P3 by switching the three switches SW1 to SW3 according to the edge detection flags flg1 to flg3. It has become.
When the PWM output stop signal S1 is Low, the switch SW4 selects the output signal of the PWM signal switching circuit 232 as shown by the solid line, and uses this as the PWM signal P ′ that is the output signal of the PWM signal output circuit 22. Output to the next LPF 23. When the PWM output stop signal S1 becomes High, the output of the PWM signal P ′ is stopped by setting the PWM signal P ′ to “0” of the GND level. That is, the switch SW4 operates as an output stop switch that turns on and off the output of the PWM signal switching circuit 232 in accordance with the edge detection flags flg1 to flg3.

Next, the operation of this embodiment will be specifically described.
First, when the PWM signal generation circuits 221 to 223 are all operating normally, and the pulse waveforms of the PWM signals P1 to P3 generated by them are the same as shown in FIGS. Will be described.
In this case, since the rise timing and the fall timing coincide with each other in the PWM signals P1 to P3, the output signals of the XOR circuits 224 to 226 are kept low. Therefore, the rising edge detection circuits 227 to 229 cannot detect the rising edge, and the edge detection flags flg1 to flg3 maintain Low as shown in FIGS.

Accordingly, the switches SW1 to SW3 of the PWM signal switching circuit 232 are in the state shown by the solid lines in FIG. 2, and the PWM signal P1 is output from the PWM signal switching circuit 232.
Further, since the edge detection flags flg1 to flg3 are Low, the PWM output stop signal S1 output from the AND circuit 231 is also Low as shown in FIG. Accordingly, the switch SW4 enters the state shown by the solid line in FIG. 2, and the PWM signal P1 output from the PWM signal switching circuit 232 is selected as the PWM signal P ′ output from the PWM signal output circuit 22 and output to the secondary LPF 23. Is done.

  Then, the PWM signal P ′ is converted into a sinusoidal excitation signal by the secondary LPF 23 and supplied to the resolver 21. Thereby, the resolver 21 is excited by the supplied excitation signal, and can detect the rotational position of the motor 20 appropriately. Further, the control unit 30 can perform appropriate steering assist control using the rotational position of the motor 20 detected by the resolver 21.

  If an abnormality occurs in the PWM signal generation circuit 221 from this normal state and the PWM signal P1 has a waveform different from that of the PWM signals P2 and P3 as shown in FIGS. ) To (f), the output signals (XOR1 and XOR3) of the XOR circuits 224 and 226 are High during the period from the time t1 to the time t2. Therefore, as shown in FIGS. 4G to 4I, the edge detection flags flg1 and flg3 are switched from Low to High at time t1, and are maintained High after time t1.

  At time t1, since the edge detection flags flg1 and flg3 are High, the switches SW1 and SW2 of the PWM signal switching circuit 232 are in the state indicated by the broken lines in FIG. At this time, since the edge detection flag flg2 is Low, the switch SW3 is in a state indicated by a solid line in FIG. As a result, the PWM signal switching circuit 232 selects and outputs the PWM signal P2.

  Since the edge detection flags flg1 and flg3 are High and the edge detection flag flg2 is Low, the PWM output stop signal S1 output from the AND circuit 231 is Low. Therefore, the switch SW4 is in the state shown by the solid line in FIG. 2, and the PWM signal P2 output from the PWM signal switching circuit 232 is output to the secondary LPF 23 as the PWM signal P ′ that is the source of the excitation signal.

  As described above, the abnormality monitoring function of the PWM signal generation circuits 221 to 223 is realized by the three XOR circuits 224 to 226 and the three rising edge detection circuits 227 to 229 corresponding thereto. When an abnormality occurs in any one of the PWM signals P1 to P3, the outputs of the two XOR circuits to which the PWM signal in which the abnormality has occurred are input in common become High, and corresponding rising edge detection is performed. The edge detection flag output from the circuit is also High. Therefore, by monitoring the edge detection flags flg1 to flg3, it is possible to identify a circuit in which an abnormality has occurred among the three PWM signal generation circuits 221 to 223.

  Further, the three changeover switches SW1 to SW3 realize a backup function when an abnormality occurs in any one of the PWM signal generation circuits 221 to 223. That is, when an abnormality occurs in any one of the three PWM signal generation circuits 221 to 223, the three PWM signal generation circuits 221 to 223 are switched to a normal PWM signal generation circuit so that normal PWM signal output can be continued. The PWM signal switching circuit 232 is configured by combining the switches SW1 to SW3. Therefore, when an abnormality occurs in the effective PWM signal generation circuit, it is possible to prevent the PWM signal in which the abnormality has occurred from being output as it is.

In this way, by combining the three PWM signal generation circuits and a simple logic circuit, it is possible to realize abnormality monitoring and backup of the PWM signal, and to improve the continuity of correct excitation signal output. As a result, the continuity of normal operation of the electric power steering device can be improved.
Similarly, a case where an abnormality has occurred in the PWM signal generation circuit 222 from a normal state will be described. In this case, when the PWM signal P2 has a waveform different from that of the PWM signals P1 and P3, the outputs of the XOR circuits 224 and 225 are output at the timing when the pulse waveform of the PWM signal P2 and the pulse waveform of the PWM signals P1 and P3 are shifted. The signals (XOR1 and XOR2) are switched to High. Therefore, the edge detection flags flg1 and flg2 are also switched to High at that timing, and the switches SW1 and SW3 are in the state indicated by the broken lines in FIG. As a result, the PWM signal switching circuit 232 outputs the PWM signal P3.

  Further, since the edge detection flags flg1 and flg2 are High and the edge detection flag flg3 is Low, the PWM output stop signal S1 is Low, and the switch SW4 is in the state shown by the broken line in FIG. Therefore, the PWM signal P3 output from the PWM signal switching circuit 232 is output to the secondary LPF 23 as the PWM signal P ′ that is the source of the excitation signal.

  Further, when an abnormality occurs in the PWM signal generation circuit 223 from the normal state and the PWM signal P3 has a waveform different from that of the PWM signals P1 and P2, the pulse waveform of the PWM signal P3 and the pulses of the PWM signals P1 and P3. The output signals (XOR2 and XOR3) of the XOR circuits 225 and 226 are switched to High at the timing when the waveform is deviated. Therefore, the edge detection flags flg2 and flg3 are also switched to High at that timing, and the switches SW2 and SW3 are in the state indicated by the broken lines in FIG. As a result, the PWM signal switching circuit 232 outputs the PWM signal P1.

  Further, since the edge detection flags flg2 and flg3 are High and the edge detection flag flg1 is Low, the PWM output stop signal S1 is Low, and the switch SW4 is in the state shown by the broken line in FIG. Therefore, the PWM signal P1 output from the PWM signal switching circuit 232 is output to the secondary LPF 23 as the PWM signal P ′ that is the source of the excitation signal.

  As described above, when an abnormality occurs in any one of the three PWM signals P1 to P3, the output signal of the PWM signal output circuit 22 is switched to one of the remaining two normal PWM signals. . Therefore, the resolver excitation circuit can generate a correct excitation signal and supply it to the resolver 21. As a result, the resolver 21 can accurately detect the rotational position of the motor 20, and the control unit 30 can appropriately control the drive of the motor 20.

  Then, from the state where an abnormality has occurred only in one of the PWM signal generation circuits 221 to 223, for example, only the PWM signal generation circuit 221, an abnormality has further occurred in the PWM signal generation circuit 222 at time t3. When the PWM signals P1 to P3 all have different waveforms as shown in FIGS. 4 (a) to 4 (c), the output signal (XOR2) of the XOR circuit 225 is at times t3 to t4 as shown in FIG. 4 (e). High. Therefore, as shown in FIG. 4 (h), the edge detection flag flg2 switches from Low to High at time t3 and maintains High after time t3.

  Thus, at time t3, since the edge detection flags flg1 to flg3 are all High, the switches SW1 to SW3 of the PWM signal switching circuit 232 are in the state indicated by the broken lines in FIG. Therefore, the PWM signal P1 is output from the PWM signal switching circuit 232. However, since all the edge detection flags flg1 to flg3 are High, the PWM output stop signal S1 output from the AND circuit 231 becomes High. As a result, the switch SW4 is in the state shown by the broken line in FIG. Therefore, the PWM signal P ′ becomes “0”, and the output of the PWM signal output circuit 22 is stopped.

  Further, even when an abnormality occurs only in the PWM signal generation circuit 221 and an abnormality further occurs in the PWM signal generation circuit 223, and the PWM signals P1 to P3 all have different waveforms, the PWM signal P2 and The output signal (XOR2) of the XOR circuit 225 switches from Low to High at the timing when the pulse waveform with the P3 is shifted, and the edge detection flag flg2 also switches from Low to High.

At this time, since all the edge detection flags flg1 to flg3 are High, the PWM output stop signal S1 output from the AND circuit 231 is High, and as a result, the switch SW4 is in the state shown by the broken line in FIG. Therefore, also in this case, the PWM signal P ′ becomes “0”, and the output of the PWM signal output circuit 22 is stopped.
Similarly, from the state where an abnormality has occurred only in the PWM signal generation circuit 222, when an abnormality has occurred in the PWM signal generation circuit 221 or 223, or from the state in which an abnormality has occurred only in the PWM signal generation circuit 223. Further, when an abnormality occurs in the PWM signal generation circuit 221 or 222, the switch SW4 is in the state shown by the broken line in FIG. 2, and the output of the PWM signal output circuit 22 is stopped.

Further, even when an abnormality occurs in all the three PWM signal generation circuits 221 to 223, the PWM output stop signal S1 becomes High and the switch SW4 is in the state shown by the broken line in FIG. Output is stopped.
That is, an abnormality occurs in all three PWM signal generation circuits 221 to 223, and an abnormality occurs in two of the three PWM signal generation circuits 221 to 223 as well as a case where a normal PWM signal generation circuit does not exist. When the normal PWM signal generation circuit cannot be specified, the output of the PWM signal output circuit 22 is stopped. Therefore, it is possible to reliably prevent the excitation signal from being generated based on the PWM signal in which an abnormality has occurred.

  As described above, in this embodiment, three PWM signal generation circuits for generating a PWM signal that is a source of the excitation signal supplied to the resolver are provided, and an XOR circuit and a rising edge detection circuit are provided for each output. Then, the abnormality of the three PWM signal generation circuits is monitored by monitoring the output of the PWM signal generation circuit by the XOR circuit and the rising edge detection circuit. Therefore, the PWM signal generation circuit in which an abnormality has occurred can be specified by a simple logic circuit.

  In addition, when an abnormality has occurred in one of the three PWM signal generation circuits, switching to the PWM signal output from the PWM signal generation circuit operating normally by the combination of the three selector switches is normal. Continue to output the correct PWM signal. Therefore, a backup function can be realized with a relatively simple circuit configuration, and a normal excitation signal can be supplied to the resolver.

  Further, when an abnormality occurs in two or more of the three PWM signal generation circuits, the output of the PWM signal from the PWM signal generation circuit is stopped by a combination of the AND circuit and the output stop switch. Therefore, the fail-safe function can be realized with a relatively simple circuit configuration, and it is possible to reliably prevent the excitation signal in which an abnormality has occurred from being supplied to the resolver.

As described above, by combining three PWM signal generation circuits and a simple logic circuit, abnormality monitoring and backup of the PWM signal generation circuit can be realized, and continuity of correct excitation signal output can be improved. it can.
When the resolver excitation circuit of the present invention is applied, a correct PWM signal is not output during the switch switching time that takes a time of the order of μsec, and during that time, angle detection by normal resolver excitation cannot be performed. However, the present invention is effective in a system such as an electric power steering apparatus in which there is no problem in the system with an abnormal behavior on the order of μsec.

  DESCRIPTION OF SYMBOLS 1 ... Steering wheel, 2 ... Column shaft, 3 ... Reduction gear, 4A, 4B ... Universal joint, 5 ... Pinion rack mechanism, 6 ... Tie rod, 10 ... Torque sensor, 11 ... Ignition key, 12 ... Vehicle speed sensor, 14 ... Battery , 20 ... motor, 21 ... resolver, 22 ... PWM signal output circuit, 23 ... secondary LPF, 30 ... control unit, 221 to 223 ... PWM signal generation circuit, 224 to 226 ... XOR circuit, 227 to 229 ... rising edge detection Circuit, 230, 231 ... AND circuit, 232 ... PWM signal switching circuit, SW1-SW3 ... changeover switch, SW4 ... output stop switch

Claims (4)

A resolver excitation circuit for supplying an excitation signal to a resolver,
Three independent PWM signal generation circuits each generating a PWM signal of the same waveform;
Three XOR circuits that input PWM signals from two of the three PWM signal generation circuits and detect the mismatch of the two PWM signals for all combinations;
Three edge detection circuits for detecting the presence or absence of rising edges of the output signals of the three XOR circuits,
A PWM signal switching circuit that selects a PWM signal generation circuit that generates a PWM signal that is a source of the excitation signal, among the three PWM signal generation circuits, based on an output of the edge detection circuit; Resolver excitation circuit.   When the output of the edge detection circuit coincides with the output when one of the three PWM signals generated by the PWM signal generation circuit is abnormal, the PWM signal switching circuit The switch is configured of three changeover switches for switching the selected PWM signal generation circuit so that any one of the two normal PWM signals becomes a PWM signal that is the source of the excitation signal. Item 12. A resolver excitation circuit according to Item 1. An AND circuit for inputting the outputs of the three edge detection circuits;
An output stop switch for turning on and off the output of the PWM signal switching circuit based on the output of the AND circuit;
In the output stop switch, the output of the AND circuit coincides with the output when an abnormality occurs in two or more of the three PWM signals generated by the PWM signal generation circuit. 3. The resolver excitation circuit according to claim 1, wherein the resolver excitation circuit is configured to stop the output of the PWM signal switching circuit. In a control device for an electric power steering apparatus, comprising: a position detection unit that detects a rotational position of a motor that assists a steering system of a vehicle; and the driving control of the motor based on steering torque and position information from the position detection unit.
The control device for an electric power steering apparatus, wherein the position detection unit includes a resolver and the resolver excitation circuit according to any one of claims 1 to 3 that supplies an excitation signal to the resolver. .

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