Monitoring device, angle detection device, and monitoring method

Abstract

To monitor and correct a change in detection accuracy due to the imbalance between N-th phases.SOLUTION: A monitoring device comprises: a monitoring unit that monitors the detection accuracy in a resolver in the N-th phase (N is an integer of 3 or more) with the square sum of sin signals and cos signals obtained through N-th phase to two phase conversion from the N-th phase output signals in the resolver; and an adjustment unit that adjusts the balance between the output signals according to the detection accuracy obtained through the monitoring.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a monitoring device, an angle detection device, and a monitoring method.

Background Art

[0002] Conventionally, an angle detection device that detects the rotation angle of a motor or the like using a resolver has been known. Also, in an angle detection device using a resolver, it is also known to have a function of monitoring temperature changes and the like. For example, in Patent Document 1, in an angle position detection device using a resolver, for the purpose of improving detection accuracy by compensating for temperature drift, by analog adding N-phase resolver signals, the modulation components of the N-phase resolver signals are canceled, and a temperature detection signal reflecting the temperature of the coil has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique of Patent Document 1, it is possible to monitor and compensate for changes in detection accuracy due to temperature drift, but it is not possible to monitor and correct changes in detection accuracy due to unbalance between N-phases. Therefore, an object of the present invention is to monitor and correct changes in detection accuracy due to unbalance between N-phases.

Means for Solving the Problems

[0005] To solve the above problems, one aspect of the monitoring device according to the present invention includes a monitoring unit that monitors the detection accuracy in an N-phase resolver (where N is an integer of 3 or more) by the sum of the squares of a sin signal and a cos signal obtained by N-phase to 2-phase conversion from the N-phase output signal of the resolver, and an adjustment unit that adjusts the balance of the output signals according to the detection accuracy obtained by monitoring.

[0006] With such a monitoring device, the detection accuracy can be accurately monitored and the imbalance corrected by the sum of the squares of the sine and cosine signals. Furthermore, in the monitoring device described above, it is preferable that the adjustment unit adjusts the output signal of the N phase that is unbalanced with respect to the other phases. By adjusting the output signal of the unbalanced phase, the imbalance between the phases can be easily corrected.

[0007] Furthermore, in the monitoring device described above, it is preferable that the adjustment unit adjusts the output signal with an adjustment amount corresponding to the difference between the maximum and minimum values ​​in the sum of squares. The difference between the maximum and minimum values ​​in the sum of squares serves as an indicator that accurately shows the imbalance between the phases, and the imbalance is accurately corrected by an adjustment amount corresponding to this difference.

[0008] Furthermore, in the above-described monitoring device, the monitoring unit preferably monitors the sum of squares E for at least one of the first electrical angle (360°÷N)×M+90° and the second electrical angle (360°÷N)×M-90° for the phase M (0 to N-1) among the N phases. If the value E increases in the first electrical angle or decreases in the second electrical angle, it is determined that the DC component has increased in the phase M. If the value E decreases in the first electrical angle or increases in the second electrical angle, it is determined that the DC component has decreased in the phase M. This determination method allows for easy and accurate identification of unbalanced phases.

[0009] To solve the above problems, one aspect of the angle detection device according to the present invention comprises an N-phase (N is an integer of 3 or more) resolver, an angle detection unit that obtains the electrical angle θ of the resolver from the output signal of the resolver, a monitoring unit that monitors the detection accuracy in the resolver by the sum of the squares of the sin signal and cos signal obtained by N-phase to 2-phase conversion from the N-phase output signal of the resolver, and an adjustment unit that adjusts the balance of the output signal according to the detection accuracy obtained by monitoring. Such an angle detection device allows for monitoring changes in detection accuracy due to imbalances between N phases and correcting those imbalances, thereby enabling highly accurate angle detection.

[0010] To solve the above problems, one aspect of the monitoring method in the monitoring device according to the present invention includes a monitoring step of monitoring the detection accuracy in an N-phase (N is an integer of 3 or more) resolver by summing the squares of a sin signal and a cos signal obtained by N-phase to 2-phase conversion from the N-phase output signal of the resolver, and an adjustment step of adjusting the balance of the output signals according to the detection accuracy obtained by monitoring.

[0011] This monitoring method allows for accurate detection accuracy and correction of imbalances by using the sum of the squares of the sine and cosine signals. [Effects of the Invention]

[0012] According to the present invention, it is possible to monitor both the change in detection accuracy due to temperature drift and the change in detection accuracy due to imbalances between N phases. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows the overall configuration of the drive unit including the angle detection device of this embodiment. [Figure 2] This is a cross-sectional view showing the structure of a resolver. [Figure 3] This graph shows the resolver signals φA, φB, and φC, and the temperature detection signal vt. [Figure 4]It is a graph showing a signal example when phase A is unbalanced with respect to other phases. [Figure 5] It is a graph showing a signal example when phase B is unbalanced with respect to other phases. [Figure 6] It is a graph showing a signal example when phase C is unbalanced with respect to other phases. [Figure 7] It is a flowchart when the signal processing of the angle detection device is realized by a program.

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described based on the drawings. However, in order to avoid the following description becoming unnecessarily redundant and to facilitate the understanding of those skilled in the art, detailed descriptions that are more detailed than necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of substantially the same configurations may be omitted. Also, elements described in the figures described above may be referred to as appropriate in the description of later figures.

[0015] In this specification, embodiments of the present disclosure will be described by taking as an example the case of monitoring the detection accuracy of a three-phase resolver having windings of three phases (phase A, phase B, and phase C). However, the case of monitoring the detection accuracy of an N-phase resolver having windings of N phases (N is an integer of 3 or more) including four phases or five phases is also within the scope of the present disclosure.

[0016] FIG. 1 is a diagram showing the overall configuration of a driving device 10 including an angle detection device 11 according to the present embodiment. FIG. 1 mainly shows the circuit configuration of the angle detection device 11. The drive device 10 includes a motor 60, a resolver 40 that outputs a resolver signal corresponding to the rotation angle of the rotation shaft of the motor 60, and a drive unit 20 that drives the motor 60. The drive unit 20 includes an angle detection device 11 that obtains a digital angle signal φ from the resolver signal, and a drive circuit 70. In FIG. 1, for the sake of convenience, the resolver 40 is shown within the block of the angle detection device 11, but in reality, the resolver 40 can be incorporated, for example, within the motor 60 to detect the rotation angle of the rotation shaft. As the motor 60, for example, a direct drive motor is suitable, but a motor other than the direct drive motor may also be used.

[0017] The drive circuit 70 drives the motor 60 based on the digital angle signal (a signal indicating the electrical angle θ) output by the angle detection device 11. The angle detection device 11 includes a transmitter 21, an amplifier 22, a current-voltage conversion circuit 23, a three-phase to two-phase converter 24, an R / D converter (resolver-digital converter) 25, a temperature detection circuit 30, and a monitoring device 50. Further, the angle detection device 11 includes signal regulators 26a, 26b, 26c, and a temperature compensator 27.

[0018] The transmitter 21 outputs an excitation signal (sine wave signal) of about several kHz. The amplifier 22 amplifies the excitation signal to an appropriate signal level and supplies it to the common terminal COM of the resolver 40. The current-voltage conversion circuit 23 converts the current signal output from the resolver 40 into a voltage signal. The three-phase to two-phase converter 24 converts a three-phase signal into a two-phase signal (sin signal, cos signal). The R / D converter 25 converts the two-phase signal into a digital angle signal (a signal indicating the electrical angle θ). That is, the electrical angle θ of the resolver 40 is obtained from the three-phase resolver signal by the three-phase to two-phase converter 24 and the R / D converter 25. The temperature detection circuit 30 outputs a temperature detection signal vt corresponding to the temperature of the resolver 40.

[0019] The monitoring device 50 is composed of, for example, a CPU (Central Processing Unit). As will be described later, the monitoring device 50 monitors the temperature and detection accuracy of the resolver 40. The temperature compensator 27 performs temperature compensation of the detection angle according to the temperature monitored by the monitoring device 50. The signal adjusters 26a, 26b, and 26c adjust the signal according to the detection accuracy monitored by the monitoring device 50.

[0020] Now, let's explain the structure of resolver 40. Figure 2 is a cross-sectional view showing the structure of resolver 40. The resolver 40 comprises a stator 43 and a hollow annular rotor 41. The resolver 40 shown as an example in Figure 2 is a VR (variable reluctance) type resolver.

[0021] The stator 43 has multiple externally toothed pole pieces 44, each having multiple pole piece teeth 45 at its tip. The pole pieces 44 are fixedly supported at points that divide the circumference equally, and three-phase coils Ca, Cb, and Cc are wound sequentially around each pole piece 44. The three-phase coils Ca, Cb, and Cc are connected in series for each phase.

[0022] The rotor 41 has internally toothed teeth 42 that are formed opposite the pole teeth 45 and are arranged in the circumferential direction. The winding directions of the coils Ca, Cb, and Cc wound around the pole pieces 44 of phases A, B, and C are set so that the polarity is reversed in adjacent pole pieces 44 of the same phase. For example, the coils are connected so that the winding direction is the same but the direction of current flow alternates between opposite directions. Alternatively, the connection direction is the same but the coil winding direction alternates between clockwise (CW) and counterclockwise (CCW).

[0023] The rotor 41 and stator 43 are concentrically arranged, and the reluctance of the gap (air gap) between the rotor 41 and stator 43 changes with the rotational angle position of the rotor 41. The fundamental wave component of the reluctance change has multiple periods (number of rotor teeth) for one rotation of the rotor 41. When an excitation signal is supplied to the common terminal of coils Ca, Cb, and Cc, the three-phase coils Ca, Cb, and Cc output A-phase, B-phase, and C-phase current signals corresponding to the rotational angle position of the rotor 41 relative to the stator 43. The A-phase, B-phase, and C-phase current signals are shifted from each other by an electrical angle of 120°.

[0024] Although an outer rotor type is shown as an example of resolver 40 in Figure 2, an inner rotor type may also be used as resolver 40. Returning to Figure 1, we continue the explanation. In an angle detection device 11 that uses a resolver 40 to detect the rotation angle of a motor 60, an imbalance in the three-phase electrical signals obtained by the resolver 40 alters the accuracy of angle detection. This change in detection accuracy due to the imbalance results in an error in the rotation control command for the motor 60, causing vibration in the motor 60's rotation and degrading smooth rotational drive. Furthermore, if positioning angle drive is performed on the motor 60, the error will cause the positioning angle to deviate by the amount of the error. Furthermore, measuring position detection accuracy is difficult when the motor is driven in a high-temperature environment. A common method for measuring position detection accuracy is to place a reference encoder opposite the resolver 40 on the motor 60 and compare and measure the detection accuracy of the motor 60 with that of the reference encoder. Additionally, it is possible to bring the accuracy of the resolver 40 closer to that of the reference encoder by correcting the error between the resolver 40 and the reference encoder. However, when the motor is rotating in a high-temperature environment, opposing placement of the reference encoder is extremely difficult. This is because having the reference encoder constantly integrated into the motor 60 for monitoring purposes presents challenges in terms of space and cost, and because the operating temperature of a high-precision reference encoder is lower than that of the resolver 40, operation in high-temperature environments becomes difficult. In the angle detection device 11 of this embodiment, with the resolver 40 mounted on the motor 60, it is possible to monitor and correct the detection accuracy even when operating in a high-temperature environment, enabling highly accurate motor control. The current-voltage conversion circuit 23 includes sense resistors Ra1, Rb1, and Rc1 for converting current signals corresponding to the rotation angles of the rotors 41 for phases A, B, and C into voltage signals (resolver signals). The resolver signals for each phase obtained by the current-voltage conversion circuit 23, ignoring higher-order components, are as shown in equations (1) to (3) below. For the sake of explanation, here we illustrate the case where the phases of phases B and C are retarded by electrical angles of 120 degrees and 240 degrees, respectively, with respect to phase A.

[0025] φA=T·(Adc+Aac·sinθ)·sinωt … (1) φB=T·{Bdc+Bac·sin(θ-120°)}·sinωt … (2) φC=T·{Cdc+Cac·sin(θ-240°)}·sinωt … (3) Here, T in equations (1) to (3) represents the temperature coefficient of the coils Ca, Cb, and Cc, and the value of the temperature coefficient T increases as the ambient temperature of the resolver 40 increases. Also, ω is the oscillation angular frequency of the oscillator 21, and θ is the electrical angle generated by the relative rotation of the rotor 41 and the stator 43.

[0026] The resolver signals for each phase are input to signal adjusters 26a, 26b, and 26c, respectively. The signal adjusters 26a, 26b, and 26c are analog calculation means. Each signal adjuster 26a, 26b, and 26c comprises an operational amplifier OP, feedback resistors Ra3, Rb3, and Rc3, input signal resistors Ra2, Rb2, and Rc2, and adjustment signal resistors Ra4, Rb4, and Rc4. The input signal resistors Ra2, Rb2, and Rc2 are provided between the current-voltage conversion circuit 23 and the non-inverting input terminal of the operational amplifier OP. The adjustment signal resistors Ra4, Rb4, and Rc4 are provided between the adjustment signal input terminals indicated by the circled numbers "1," "2," and "3" and the non-inverting input terminal of the operational amplifier OP. The adjustment signals are added to the resolver signals of each phase by the signal adjusters 26a, 26b, and 26c. The adjustment signals are signals that adjust the DC component in the resolver signals of each phase. Details of the adjustment signals will be described later.

[0027] The three-phase resolver signals, after passing through signal adjusters 26a, 26b, and 26c, are input to the three-phase to two-phase converter 24 and converted into two-phase signals. Equations (4) and (5) below show the two-phase signals sin and cos obtained by the three-phase to two-phase converter 24. sin signal=φA-(φB+φC) / 2 … (4) cos signal=sqr(3 / 4)·(φB-φC) … (5)

[0028] In equation (5), sqr(x) is a function that returns the square root of the argument x. The two-phase signal obtained by the three-phase two-phase converter 24 is input to the R / D converter 25. The R / D converter 25 converts the two-phase signal into a digital angle signal. The angle signal represents the electrical angle θ, and after temperature compensation by the temperature compensator 27, it is output from the angle detection device 11 and input to the drive circuit 70. The drive circuit 70 has the function of calculating the rotation angle at the rotation axis of the motor 60 from the electrical angle θ.

[0029] The three-phase resolver signals, after passing through signal regulators 26a, 26b, and 26c, are also input to the temperature detection circuit 30. The temperature detection circuit 30 includes an analog summing circuit 31, a demodulator 32, and an A / D converter 33. The analog summing circuit 31 is an analog calculation means and includes an operational amplifier OP, a feedback resistor Rf, and resistors Ra5, Rb5, and Rc5. The resistors Ra5, Rb5, and Rc5 are provided between the signal adjusters 26a, 26b, and 26c and the non-inverting input terminals of the operational amplifier OP.

[0030] The analog summing circuit 31 adds the resolver signals φA, φB, and φC and outputs a temperature detection signal vt. The demodulator 32 demodulates the modulation component (sinωt) of the temperature detection signal vt to obtain a DC amplitude voltage VT. The A / D converter 33 converts the amplitude voltage VT into a digital value.

[0031] Figure 3 is a schematic graph showing the resolver signals φA, φB, and φC and the temperature detection signal vt. Figure 3 shows each signal as an envelope with the modulation component (sinωt) abstracted away. In the graph in Figure 3, the horizontal axis represents the electrical angle θ, and the vertical axis represents the signal intensity. The three-phase resolver signals φA, φB, and φC are out of phase by 120 degrees from each other, and the temperature detection signal vt, which is the sum of the three-phase resolver signals φA, φB, and φC, is a constant value independent of the electrical angle θ, as shown in Figure 3. Even if the DC components in the three-phase resolver signals φA, φB, and φC become unbalanced among the three phases, the temperature detection signal vt remains constant. The amplitude voltage VT obtained from the temperature detection signal vt via the demodulator 32 and A / D converter 33 represents the temperature coefficient T of the coils Ca, Cb, and Cc, and the ambient temperature.

[0032] The amplitude voltage VT output from the temperature detection circuit 30 shown in Figure 1 is input to the temperature monitoring unit 51 of the monitoring device 50. The temperature monitoring unit 51 monitors the ambient temperature indicated by the amplitude voltage VT and calculates a temperature compensation value for the digital angle signal indicating the electrical angle θ based on the ambient temperature using any conventionally known method. From another perspective, the temperature monitoring unit 51 monitors the ambient temperature in the resolver 40 by summing the N-phase output signals of the N-phase (e.g., 3-phase) resolver 40. The temperature compensation value calculated by the temperature monitoring unit 51 is input to the temperature compensator 27, as indicated by the circled number "4", and is used for temperature compensation for the digital angle signal.

[0033] The two-phase signals sin and cos obtained by the three-phase two-phase converter 24 are converted into digital two-phase signals SIN and COS via the demodulator 34 and A / D converter 35, and input to the sum of squares calculation unit 52 of the monitoring device 50. The sum of squares calculation unit 52 calculates the sum of squares E shown in the following equation (6).

[0034] E = sin 2 θ+cos 2 θ … (6) The sum of squares E is input to the detection accuracy monitoring unit 53 of the monitoring device 50, and the detection accuracy monitoring unit 53 monitors the detection accuracy based on the sum of squares E. In other words, the detection accuracy monitoring unit 53 monitors the detection accuracy in the resolver 40 by the sum of squares of the sin signal and cos signal obtained from the N-phase output signal by N-phase to 2-phase conversion. The detection accuracy monitoring unit 53 has a monitoring unit 54, a phase identification unit 55, and an adjustment value setting unit 56.

[0035] The monitoring unit 54 of the detection accuracy monitoring unit 53 monitors for the presence or absence of imbalance between the phases of the resolver signal based on the sum of squares E. Specifically, it determines the presence or absence of imbalance by whether or not the value of the sum of squares E causes fluctuations dependent on the electrical angle θ. From another perspective, the monitoring unit 54 monitors the detection accuracy using the difference between the maximum and minimum values ​​in the sum of squares E as an indicator. When the difference between the maximum and minimum values ​​exceeds a threshold, the monitoring unit 54 determines that an imbalance has occurred between the phases, resulting in a decrease in detection accuracy.

[0036] If an imbalance occurs and detection accuracy decreases, the phase identification unit 55 identifies the phase that has become unbalanced relative to the other phases. The adjustment value setting unit 56 sets the adjustment amount to correct the imbalance for the identified phase in the signal adjusters 26a, 26b, and 26c. That is, the adjustment signal corresponding to the adjustment amount calculated by the adjustment value setting unit 56 is output from the monitoring device 50 as shown by the circled numbers "1", "2", and "3", and input to the signal adjusters 26a, 26b, and 26c. The adjustment signal is added to the resolver signal in the signal adjusters 26a, 26b, and 26c, correcting the phase imbalance and improving detection accuracy.

[0037] Here, the specific processing in the detection accuracy monitoring unit 53 will be explained based on a signal example. Figures 4 to 6 are schematic graphs illustrating signal examples when an imbalance occurs between phases. Each graph in Figures 4 to 6 shows the two-phase signals SIN, COS, and sum of squares E. Figure 4 shows the case where phase A is unbalanced with respect to the other phases. Figure 5 shows the case where phase B is unbalanced with respect to the other phases, and Figure 6 shows the case where phase C is unbalanced with respect to the other phases. In each graph in Figures 4 to 6, the horizontal axis represents the electrical angle, and the vertical axis represents the signal strength.

[0038] When phase A is unbalanced with respect to the other phases, the signal strength of the sum of squares E shows a minimum or maximum at electrical angles of ±90 degrees from 0 degrees. That is, when the DC component of phase A is larger than that of the other phases, it shows a maximum at 90 degrees and a minimum at 270 degrees, as shown in Figure 4(A). Also, when the DC component of phase A is smaller than that of the other phases, it shows a minimum at 90 degrees and a maximum at 270 degrees, as shown in Figure 4(B).

[0039] When phase B is unbalanced with respect to the other phases, the signal strength of the sum of squares E shows a minimum or maximum at electrical angles of ±90 degrees from 120 degrees. That is, when the DC component of phase B is larger than that of the other phases, it shows a maximum at 210 degrees and a minimum at 30 degrees, as shown in Figure 5(A). Also, when the DC component of phase B is smaller than that of the other phases, it shows a minimum at 210 degrees and a maximum at 30 degrees, as shown in Figure 5(B).

[0040] When phase C is unbalanced with respect to the other phases, the signal strength of the sum of squares E shows a minimum or maximum at electrical angles of ±90 degrees from 240 degrees. That is, when the DC component of phase C is larger than that of the other phases, it shows a maximum at 330 degrees and a minimum at 150 degrees, as shown in Figure 6(A). Also, when the DC component of phase B is smaller than that of the other phases, it shows a minimum at 330 degrees and a maximum at 150 degrees, as shown in Figure 6(B).

[0041] The monitoring unit 54 of the detection accuracy monitoring unit 53 shown in Figure 1 monitors the detection accuracy using the difference between the maximum and minimum values ​​in the sum of squares E as an indicator. If the difference between the maximum and minimum values ​​exceeds a threshold, it is determined that an imbalance has occurred between the phases and the detection accuracy has decreased. The phase identification unit 55 identifies the phase that has become unbalanced with respect to the other phases based on the electrical angle θ at which the sum of squares E shows a maximum or minimum value.

[0042] Specifically, the phase identification unit 55 monitors the sum of squares E of at least one of the first electrical angle (360°÷N)×M+90° and the second electrical angle (360°÷N)×M-90° for the phases with phase numbers M(0~N-1) in the N-phase resolver. The phase identification unit 55 then determines that the DC component has increased in the phase with phase number M if the value E increases in the first electrical angle or decreases in the second electrical angle. The phase identification unit 55 also determines that the DC component has decreased in the phase with phase number M if the value E decreases in the first electrical angle or increases in the second electrical angle.

[0043] The adjustment value setting unit 56 calculates an adjustment amount corresponding to the difference between the maximum and minimum values, as an adjustment amount according to the detection accuracy. The adjustment value setting unit 56 then inputs the adjustment signal to the signal adjusters 26a, 26b, and 26c of the phase that is unbalanced with respect to the other phases, as identified by the phase identification unit 55. As a result, the signal adjusters 26a, 26b, and 26c adjust the output signal of the phase that is unbalanced with respect to the other phases by an adjustment amount corresponding to the difference between the maximum and minimum values ​​in the sum of squares. Here, we will explain specific examples of adjustment amounts. For example, if the DC component Adc in the resolver signal φA of phase A is 10.1V, and the DC components Bdc and Cdc of phases B and C are both 10V, then sin 2 θ+cos 2 The waveform at θ=E is, Electrical angle 0 degrees (=360 degrees): 4.02[V] 2 ] The electrical angle of 90 degrees is the maximum: 4.55[V] 2 ] Minimum electrical angle of 270 degrees: 3.48[V] 2 ] As described above, the electrical angles of the maximum and minimum values ​​of the waveform confirm that an imbalance occurs in phase A and that the positive or negative sign of the imbalance is present. Furthermore, an adjustment amount obtained by multiplying the difference between the maximum and minimum values ​​= 4.55 - 3.48 = 1.07 by a predetermined coefficient is input to the phase A signal regulator 26a by the adjustment value setting unit 56, and at least a portion of the imbalance is corrected. The coefficient is set to a value corresponding to the resolver 40 and motor 60. Through repeated unbalance correction using these adjustment values, the DC component Adc in the A-phase resolver signal φA becomes 0.1V lower, and as a result, the waveform of the sum of squares E becomes 4.00[V] across the entire electrical angle. 2 ] The imbalance between the phases is corrected by adjusting the three-phase resolver signals. Therefore, the temperature monitoring unit 51 monitors the detection accuracy in the resolver 40 using the sum of squares obtained from the three-phase resolver signals adjusted based on the monitoring results of the detection accuracy monitoring unit 53. Imbalances between phases affect the accuracy of angle detection by the resolver 40, as well as the accuracy of temperature monitoring and temperature compensation to respond to changes in ambient temperature. Therefore, it is desirable to improve the accuracy of drive control of the motor 60 by correcting the imbalance. In the angle detection device 11 shown in Figure 1, the adjustment signals input to the signal adjusters 26a, 26b, and 26c correct the imbalance between phases, thereby improving the accuracy of detecting the electrical angle θ. This also improves the accuracy of the temperature detection signal vt, thus improving the accuracy of temperature compensation. Consequently, the accuracy of the digital angle signal indicating the electrical angle θ is improved, and the accuracy of drive control for the motor 60 is also improved.

[0044] In the angle detection device 11 shown in Figure 1, hardware-based calculation means are used for the temperature detection circuit 30, etc. However, the angle detection device 11 may also perform signal processing using a program that uses the configuration shown in Figure 1 as an equivalent circuit.

[0045] Figure 7 is a flowchart showing the case where the signal processing of the angle detection device 11 is implemented by program. When the program starts, in step S101, three-phase resolver signals φA, φB, and φC are acquired from resolver 40. Then, in step S102, the three-phase resolver signals φA, φB, and φC are converted into two-phase signals (sine and cosine signals), and the electrical angle θ is calculated.

[0046] Subsequently, the processes in steps S103 to S106 and steps S107 to S109 are executed in parallel. In step S103, the sum of squares E is calculated from the two-phase signal, and in step S104, the detection accuracy is monitored based on the sum of squares E. In other words, in step S104, the detection accuracy in resolver 40 is monitored by the sum of squares of the sin and cos signals obtained from the N-phase (e.g., three-phase) output signal by N-phase to 2-phase conversion.

[0047] In step S105, the phase experiencing imbalance is identified based on the presence of a maximum or minimum in the sum of squares E at the electrical angles corresponding to the phase number. In step S106, the resolver signal of the identified phase is adjusted based on the difference between the maximum and minimum in the sum of squares E. In other words, in step S106, the balance of the output signal is adjusted according to the detection accuracy obtained through monitoring.

[0048] In step S107, the three-phase resolver signals φA, φB, and φC are added together, and in step S108, temperature monitoring is performed based on the added value. In other words, in step S108, the ambient temperature at the resolver 40 is monitored by the sum of the N-phase output signals at the N-phase (e.g., three-phase) resolver 40. In step S109, temperature compensation is performed according to the monitored temperature.

[0049] In the angle detection device 11, temperature information and detection accuracy information are acquired solely through the calculation processing of the resolver signal. Therefore, temperature monitoring and detection accuracy monitoring functions are realized without increasing the number of motor components. This simplifies system design, saves space and makes the angle detection device 11 more compact, and increases the reliability of the system.

[0050] The object of angle detection is not limited to direct drive motors; for example, the angle position detection device 11 may be incorporated into the electric power steering system of a vehicle to detect the steering angle. [Explanation of Symbols]

[0051] 10...Drive unit, 11...Angle detection device, 20...Drive unit, 21...Transmitter, 22... Amplifier, 23... Current-voltage conversion circuit, 24... 3-phase 2-phase converter, 25... R / D converter, 26a, 26b, 26c... Signal regulators, 27... Temperature compensator, 30... Temperature detection circuit, 31...Analog summing circuit, 32, 34...Demodulator, 33, 35...A / D converter, 40...Resolver, 50...Monitoring device, 51...Temperature monitoring unit, 52...Sum of squares calculation unit, 53...Detection accuracy monitoring unit, 54...Monitoring unit, 55...Phase identification unit, 56...Adjustment value setting unit, 60...Motor, 70...Drive circuit

Claims

1. A monitoring unit monitors the detection accuracy of an N-phase resolver (where N is an integer greater than or equal to 3) by summing the squares of the sine and cosine signals obtained from the N-phase output signal of the N-phase resolver through N-phase to 2-phase conversion. An adjustment unit that adjusts the balance of the output signal according to the detection accuracy obtained by monitoring, A monitoring device equipped with, The adjustment unit is a monitoring device that adjusts the output signal by an adjustment amount corresponding to the difference between the maximum and minimum values ​​in the sum of squares.

2. The monitoring device according to claim 1, characterized in that the adjustment unit adjusts the output signal of the N phase that is unbalanced with respect to the other phases.

3. The monitoring unit monitors the sum of squares E for at least one of the first electrical angle (360° ÷ N) × M + 90° and the second electrical angle (360° ÷ N) × M - 90° for the phase M (0 to N-1) among the N phases, and determines that the DC component has increased in the phase M if the value E increases in the first electrical angle and decreases in the second electrical angle, and determines that the DC component has decreased in the phase M if the value E decreases in the first electrical angle and increases in the second electrical angle, as described in claim 1.

4. The monitoring device according to claim 1, further comprising a temperature monitoring unit that monitors the ambient temperature in the resolver by the sum of the output signals adjusted by the adjustment unit.

5. An N-phase resolver (where N is an integer greater than or equal to 3), An angle detection unit that obtains the electrical angle θ of the resolver from the output signal of the resolver, A monitoring unit monitors the detection accuracy of the resolver by the sum of the squares of the sine and cosine signals obtained by N-phase to 2-phase conversion from the N-phase output signal of the resolver. An adjustment unit that adjusts the balance of the output signal according to the detection accuracy obtained by monitoring, An angle detection device equipped with, The adjustment unit is an angle detection device that adjusts the output signal by an adjustment amount corresponding to the difference between the maximum and minimum values ​​in the sum of squares.

6. A monitoring step involves monitoring the detection accuracy of an N-phase resolver (where N is an integer greater than or equal to 3) by measuring the sum of the squares of the sine and cosine signals obtained from the N-phase output signal of the N-phase resolver through N-phase to 2-phase conversion, and An adjustment step to adjust the balance of the output signal according to the detection accuracy obtained by monitoring, A monitoring method in a monitoring device having, The adjustment step is a monitoring method that adjusts the output signal with an adjustment amount corresponding to the difference between the maximum and minimum values ​​in the sum of squares.

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