JP2011257254A - Rotation angle detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a rotation position by using a simple constitution and irrespective of variance in transformation ratio of a resolver and the number of rotations of a rotor.SOLUTION: A rotation angle detection device includes: means for alternately sampling two detection signals S1 and S2 of a resolver; means for determining whether a rotary electric machine is in a state of stop or is rotating at low speed; means for calculating, when the rotary electric machine is in a state of stop or is rotating at low speed, the rotation position angle by the inverse function of tangent based on the signal obtained by the sampling means; means for obtaining, from the signal obtained by the sampling means, the amplitude A of the signal based on the obtained rotation position angle information; and means for storing the amplitude A. When the state of the rotary electric machine is determined otherwise, the rotation position angle is calculated by the inverse function of sine or cosine based on the signal obtained by the sampling means and the stored amplitude A.

Description

  The present invention relates to an apparatus for detecting the rotational position of a rotor.

  The resolver has a one-phase excitation input and a two-phase output, and the first resolver signal S1 and the second resolver signal S2 output from the resolver are input to the RD converter that detects the rotational position and from the excitation signal generator. An excitation signal is input to the resolver and the RD converter.

JP 2009-150826 A

  Here, the general operation of the RD converter will be described based on the description in Patent Document 1. As shown in FIG. 4, the RD converter includes a first multiplier 118, a second multiplier 119, a subtractor 112, a synchronous detection circuit 113, a band elimination filter 114, a controller 115, a sin function, and a cos function lookup table. (Stored in the ROM) 116, 117. The RD converter converts the detection angle θ of the resolver detection signals S1 and S2 into a digital angle output φ in the angle calculation loop having the above-described configuration, and outputs the digital angle output φ.

  The sin function lookup table 117 in the RD converter generates a sine value sinφ based on the digital angle output φ and outputs it to the multiplier 119, and the cos function lookup table 116 calculates the cosine value cosφ based on the digital angle output φ. And output to the multiplier 118.

  Multiplier 118 multiplies resolver detection signal S1 and cosφ, and outputs the multiplication value to subtractor 112. Multiplier 119 multiplies resolver signal S2 and sinφ, and provides the multiplication value to subtractor 112. Output. The subtractor 112 subtracts the output of the multiplier 119 from the output of the multiplier 118 and outputs the subtraction value to the synchronous detection circuit 113.

Here, if the resolver signals S1 and S2 are set to the signal amplitude A determined by the transformation ratio of the resolver and the excitation signal is sinωt,
S1: A · sinθsinωt, S2: A · cosθsinωt Equation (1)
Therefore, the output of the subtractor is
A · (sinθcosφ−cosθsinφ) sinωt = A · sin (θ−φ) sinωt Equation (2)
The synchronous detection circuit 113 refers to the excitation signal input from the excitation signal generation unit, synchronously detects the output of the subtractor 112, and outputs the detection output to the band elimination filter 114 in this example. The detection output that has passed through the band elimination filter 114 is input to the controller 115, and the controller 115 is digital so that the detection output becomes zero, that is, the control deviation sin (θ−φ) that is the detection output becomes zero. By controlling the angle output φ and setting the control deviation sin (θ−φ) to zero, the detected angle θ is converted into a digital angle output φ. According to this series of processing of the RD converter, the angle can be detected without being affected by variations in the amplitude A included in the resolver detection signals S1 and S2. The conventional RD converter requires two signal inputs that can process the resolver detection signals S1 and S2 in the same series, and further requires a multiplier, synchronous detection, a filter, and a controller that makes the detection output zero. There is a problem that the configuration becomes complicated.

  An object of the present invention is to simplify a configuration necessary for calculating a rotational position angle and to provide a low-cost rotational angle detection device.

  It is another object of the present invention to provide an apparatus for accurately detecting the rotational position regardless of variations in the transformer transformation ratio and the rotational speed of the rotating body.

  A rotation angle detection device according to the present invention is a rotation angle detection device having a detector that detects a rotation position of a rotor of a rotating electrical machine, wherein the detector outputs first and second detection signals, and The output first and second detection signals are output to a detection signal selection circuit, and when the rotating electrical machine is stopped or when the rotational speed of the rotating electrical machine is a predetermined value or less, the detection signal selection circuit Alternately outputs the first and second detection signals, the sample detection means detects the alternately output detection signals at a predetermined timing, and the arithmetic circuit detects the detection signal based on the signals detected at the predetermined timing. The rotational position angle of the rotor is calculated.

  ADVANTAGE OF THE INVENTION According to this invention, the structure required for a rotation position angle calculation can be simplified and a low-cost rotation angle detection apparatus can be provided.

The block diagram for implementing this invention. The flowchart which shows the content processed with CPU of FIG. The flowchart of the process A called from the flowchart of FIG. The flowchart of the process B called from the flowchart of FIG. Waveform showing the problem when simultaneous sampling is not performed. The block diagram of a conventionally well-known.

  In addition to the contents described in the column of the problem to be solved by the invention and the column of the effect of the invention, in the following embodiments, a desirable problem can be solved in commercialization, and a favorable effect in commercialization. Play. Some of them will be described next, and in the description of the embodiments, specific solutions to problems and specific effects will be described.

  Hereinafter, the rotation angle detection device of the present invention will be described in detail with reference to an embodiment.

〔Example〕
FIG. 1 shows an example of a configuration for carrying out the present invention.

  A positive electrode side connection point S11 of the detection unit S10 that detects the position of the rotor is connected to a connection point AS1 via a resistor R13. The connection point AS1 is a connection point between the other end of the resistor R11 whose one end is connected to the reference potential VCC and the other end of R12 whose one end is connected to the ground. Further, the negative electrode side connection point S12 of the detection unit S10 is connected to the ground. Similarly, the positive electrode side connection point S21 of the detection unit S20 that detects the position of the rotor is connected to the connection point AS2 via the resistor R23. The connection point AS2 is a connection point between the other end of the resistor R21 whose one end is connected to the power supply VCC and the other end of R22 whose one end is connected to the ground. Further, the negative electrode side connection point S22 of the detection unit S20 is connected to the ground. AS1 and AS2 are connected to analog input terminals AN1 and AN2 of the microcomputer, respectively.

  Here, when the amplitude (0-peak) of the detection signals S1 and S2 is 3 · Vcc, if R11 = R12, 5 · R13 = R12, R21 = R22, 5 · R23 = R22, then AN1 and AN2 A signal that changes from 0 to VCC around VCC / 2 is input.

  AN1 and AN2 are selectively connected to an AD converter 203 via a sample hold 202 in a multiplexer 212 in the microcomputer. The reference signal of the AD converter 203 is connected to VCC. The AD converter has 10-bit resolution, and the conversion result is linearly converted from 0 (0 (V)) to 3FF (VCC (V)) according to the input voltage.

  The detection signals S1 and S2 are alternately converted into digital signals in response to the trigger 204 of the AD converter 203. When the conversion is completed, the detection signals S1 and S2 are mounted on the microcomputer, and in accordance with the contents scheduled in advance at the initialization. The conversion result is transferred to the RAM 211 at a predetermined address by the (direct memory access) function. Based on the result, the CPU 209 calculates the rotational position angle based on the software stored in the ROM 210.

  The excitation signal is supplied from the oscillator 111 to the resolver and input to the comparator, and the pulse train obtained by converting the excitation signal into a zero cross signal is connected to the external trigger terminal 204 of the AD converter of the microcomputer through a delay circuit. ing.

  As described above, the detection signals S1 and S2 detected by the detection units S10 and S20 are alternately selected and output by the multiplexer 212. That is, when the detection signal S1 is selected, the detection signal S2 is selected next time. The rotation angle is calculated by the signals S1 and S2 which are alternately selected in this way.

  By using a method of processing information based on the result of alternately sampling the two detection signals S1 and S2, it is possible to employ a single signal input for processing the resolver signals S1 and S2 in time series. Multiplier, synchronous detection, filter, and controller to make detection output zero, which are necessary when detecting with two systems, are eliminated, and the configuration can be simplified and the rotation angle detector is inexpensive. Can be provided.

  Here, it demonstrates in detail. FIG. 3A shows the excitation signal supplied to the resolver. FIG. 3B shows detection signals S1 and S2 when the rotating body to which the resolver is attached is stopped. Assuming that there is only one detection input system, the sample hold is sampling the detection signal S1 (white circle in the figure) and detection signal S2 (black circle in the figure) alternately in synchronization with the positive peak of the excitation signal. Indicates.

  Since it is stopped, the envelope of the excitation signal component that appears in the detection signal is DC. Therefore, in this state, there is no influence on the detected values S1 and S2 of the envelope due to the difference between the sample points of S1 and S2.

  FIGS. 3C and 3D respectively show detection signals S1 and S2 when the rotating body rotates at a low speed and at a high speed. Comparing the two figures, it can be seen that as the number of rotations increases, the difference between the rotation angles indicated by the detection signals S1 and S2 increases due to the influence of the sampling time.

  That is, focusing on the sampling point Ps of the detection signal S2 in the diagram at the time of low-speed rotation, the sampling point of the detection signal S1 with the sampling point delayed by one excitation wave period compared to the case where the detection signals S1 and S2 are sampled simultaneously. In the meantime, an error δ occurs. Similarly, when the error δ between the sample point Pf and the sample point Qf in the drawing at high speed rotation is compared, it can be seen that the difference is increased. Since the rotation angle is calculated from Equation 2, the error δ due to different sample points appears as a rotation angle error.

  In the present invention, a single signal input as shown in FIG. 1 is adopted, and at the time of stop where an error in rotation angle detection does not occur even when time series processing of two signals is performed, or low-speed rotation that allows the error to be small. In the region, the rotation angle is calculated by subjecting the ratio of the two detection signals S1, S2 to inverse tangent function processing. By taking the ratio of S1 and S2, the influence of the signal amplitude A on the rotation angle can be eliminated. With the above-described configuration, the rotation angle can be calculated with high reliability while simplifying the circuit configuration.

  Further, the amplitude A is obtained and stored by the obtained rotation angle and the detection signal S1 or S2, and S1 or S2 is selected at high speed rotation, and the rotation angle is calculated by the selected signal and amplitude A. Since only one signal is required to calculate the rotation angle, it is possible to provide a rotation angle detection device with little decrease in angle calculation accuracy due to the influence of the sampling time.

  Here, software processing executed by the CPU 209 will be described with reference to the flowchart of FIG.

  When this process is started, each digital value is read by referring to the address of the RAM 211 where the digital conversion results of the S1 and S2 signals are stored by the AD converter in step T1. The difference between the result read in step T2 and the previous read value stored in the subsequent stage of this process is calculated. If the calculation result is less than or equal to a predetermined value in step T3, it is determined that the operation is stopped or rotating at a low speed, and the process A is called in step T4. Otherwise, it is determined that high-speed rotation is in progress, and process B is called at step T5.

  If the CPU 209 determines that the operation is stopped or is rotating at a low speed, the process A is executed. If the rotation position angle is S1, the read value of the sample signal of S1 is S1 (n) and the read value of the sample signal of S2 is S2 (n). , The rotational position angle θn is calculated by Equation 3. This can be executed by a series of processing from step T10 to step T43 in the flowchart shown in FIG.

If S1 (n) ≧ 0, S2 (n) ≧ 0, and | S1 (n) | <| S2 (n) |
θn = tan ⁻¹ (| S1 (n) | / | S2 (n) |)
Otherwise,
If S1 (n) ≧ 0, S2 (n) ≧ 0, and | S1 (n) | ≧ | S2 (n) |
θn = π / 2−tan ⁻¹ (| S2 (n) | / | S1 (n) |)
Otherwise,
If S1 (n) <0, S2 (n) ≧ 0, and | S1 (n) | <| S2 (n) |
θn = 2π−tan ⁻¹ (| S1 (n) | / | S2 (n) |)
Otherwise,
If S1 (n) <0, S2 (n) ≧ 0, and | S1 (n) | ≧ | S2 (n) |
θn = 3π / 2 + tan ⁻¹ (| S2 (n) | / | S1 (n) |)
Otherwise,
If S1 (n) ≧ 0, S2 (n) <0, and | S1 (n) | <| S2 (n) |
θn = 2π−tan ⁻¹ (| S1 (n) | / | S2 (n) |)
Otherwise,
If S1 (n) ≧ 0, S2 (n) <0, and | S1 (n) | ≧ | S2 (n) |
θn = π / 2 + tan ⁻¹ (| S2 (n) | / | S1 (n) |)
Otherwise,
If S1 (n) <0 and S2 (n) <0 and | S1 (n) | <| S2 (n) |
θn = 2π−tan ⁻¹ (| S1 (n) | / | S2 (n) |)
Otherwise,
If S1 (n) <0 and S2 (n) <0 and | S1 (n) | ≧ | S2 (n) |
θn = 3π / 2−tan ⁻¹ (| S2 (n) | / | S1 (n) |) Equation (3)
Next, the amplitude A is calculated according to the equation (4) for each condition and stored in the RAM at a predetermined address. This can be executed by a series of processing from step T50 to T60 in the flowchart shown in FIG. Here, by selecting a signal having a large value of the detection signals S1 and S2, it is possible to suppress a quantization error in digital calculation.
If | sinθn |> | cosθn |, A = S1 (n) / (sinθn)

In other cases, A = S2 (n) / (cosθn) (4)
On the other hand, when it is determined that the rotation is at a high speed, the process B is executed, and the rotational position angle θn is calculated by an equation. This can be executed by a series of processes from step T70 to T72 in the flowchart shown in FIG.
When | S1 (n) | <| S2 (n) |, θn = sin ⁻¹ (S1 (n) / A)

Otherwise, θn = cos ⁻¹ (S2 (n) / A) (5)
When the process A or the process B is completed, the values S1 (n) and S2 (n) detected this time are set as the previous detection values S1 (n-1) and S2 (n-1) in step T6 of the flowchart of FIG. The motor current control process is called at step T7. When the motor current control process ends, the process returns to the main process at step T8, and the process of FIG. 2 ends.

  The series of processing shown in FIG. 2 is executed for each motor current control calculation at a predetermined timing, for example, when a resolver is attached to the motor and its control is performed. In this embodiment, a configuration is adopted in which the current control is started by an external interrupt, and the flowchart processing of FIG. 2 is executed as part of the processing.

  The present invention can be applied to a rotational position angle detector other than a resolver that outputs sin θ and cos θ in response to the rotational position angle θ.

  For example, a rotation detector as shown in FIG. 5 can be considered. The disk 300 attached to the rotating body for detecting the rotational position shown in FIG. 5a is a magnetic body (permanent magnet) having a sinusoidal magnetization on its outer periphery. A predetermined gap is maintained from the magnetic material, and the Hall element A301 and the Hall element B302 are arranged on the outer periphery of the disk so that the sine wave output of each element has a phase angle of 90 degrees.

  In this rotational position angle detector, since a permanent magnet is used, an excitation circuit such as a resolver is unnecessary, and a Hall element is used, so even when it is stopped, it responds to the amount of magnetic flux from the magnet. A signal corresponding to the rotational position angle can be obtained as shown in FIG.

  Therefore, the oscillator 111, the comparator 200, and the delay circuit 201 in FIG. 1 can be omitted. In this case, instead of the external trigger, the AD conversion may be started at a predetermined interval by a timer built in the microcomputer.

  As described above, the present embodiment provides a rotation angle detection device that uses a simple circuit configuration and accurately detects the rotational position regardless of variations in the transformation ratio of the resolver and the rotational speed of the rotating body. be able to.

DESCRIPTION OF SYMBOLS 100 Signal processor 110 Resolver 111 Oscillator 112 Multiplier 113 Synchronous detector 114 Band elimination filter 115 Controller 116 Subtractor 117 Cos function lookup table 118 Sine function lookup table 120 Microcomputer 200 Zero cross comparator 201 Delay circuit 202 Sample hold device 203 AD converter 204 AD converter external trigger terminal 205 Conversion result register 206 External interrupt terminal 207 Interrupt controller 208 DMA
209 CPU
210 ROM
211 RAM
212 multiplexer

Claims (3)

A rotation angle detection device having a detector for detecting a rotation position of a rotor of a rotating electrical machine,
The detector outputs first and second detection signals;
The output first and second detection signals are output to a detection signal selection circuit,
When the rotating electrical machine is stopped, or when the rotational speed of the rotating electrical machine is equal to or less than a predetermined value, the detection signal selection circuit alternately outputs the first and second detection signals,
The sample detection means detects the alternately output detection signals at a predetermined timing,
The arithmetic circuit calculates the rotational position angle of the rotor based on the signal detected at the predetermined timing and calculates the amplitude based on the first or second detection signal and the calculated rotational position angle. And an angle storage means for storing the rotation angle detecting device. A rotation angle detection device having a detector for detecting a rotation position of a rotor of a rotating electrical machine,
The detector outputs first and second detection signals;
The output first and second detection signals are output to a detection signal selection circuit,
When the rotational speed of the rotating electrical machine is a predetermined value or more, the detection signal selection circuit alternately outputs the first and second detection signals,
The sample detection means detects the alternately output detection signals at a predetermined timing,
An arithmetic circuit calculates a rotational position angle of the rotor based on a signal detected at the predetermined timing and information stored in the amplitude storage means. The rotation angle detection device according to claim 1 or 2,
The detector outputs the first and second detection signals based on a detector excitation signal output by an oscillator;
The rotation angle detection device according to claim 1, wherein the sample detection means detects the first and second detection signals after a predetermined delay time from the point where the detector excitation signal becomes zero.

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