JPH0781879B2 - Rotation detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a rotation detecting device for detecting the position and speed of a rotating body such as an electric motor.

(Prior Art) Synchronous electric machines called resolvers, celsins, etc. are widely used for rotation detection of electric motors because they have the same structure as electric motors and have high reliability. Generally, to configure a rotation detection device using a synchro electric machine, it is necessary to combine it with a converter such as a synchro / digital converter (S / D converter) or a resolver / digital converter (R / D converter).

There are two typical types of these converters. One is a system called a tracking converter, such as 1S14, 1S24, 1S44, 1S64 manufactured by Analog Devices, Inc. When the primary winding of the synchro electric machine is single-phase excited, an induced voltage signal having an amplitude determined by the sine wave and cosine wave functions according to the rotational position is generated in the two-phase secondary winding. In the converter, a kind of phase-locked loop is used so that the sine wave and cosine wave signals created from the count value of the up / down counter follow the amplitude of the induced voltage signal that changes sinusoidally due to the change of the rotational position. It is configured. The count value of the up / down counter operates so as to follow the rotation position, and by reading this count value, the rotation position can be obtained as a value converted into a digital value. Although this method can read the rotational position at any time, it has a complicated configuration, is costly, and has many analog parts, making it difficult to form an integrated circuit.

The other one is a system called a phase detection converter. When the two-phase primary winding of the synchro electric machine is excited by the two-phase sine wave signal, a sinusoidal induced voltage signal whose phase changes according to the rotational position is generated in the secondary winding. The rotational position is detected by detecting the phase change of the induced voltage signal with respect to the excitation sine wave signal.

The basic structure is shown in FIG. 1 is a clock generation circuit, 2 is a counter circuit, 3 is a function circuit, 4 is a synchro electric machine (resolver), 5 is a filter circuit, 6 is a comparator circuit, 7
Is a flip-flop circuit, and 8 is a latch circuit.

The clock pulse output from the clock generation circuit 1 is counted by the counter circuit 2, and the count value θ _o increases with time. The count value theta _o is inputted to the function circuit 3, two phases in accordance with the count value theta _o sinusoidal signal SIN _o, COS .theta _o is output. The function circuit 3 can be composed of, for example, a read only memory (ROM) in which sine wave and cosine wave functions are written and a digital / analog converter. The synchro electric machine 4 is excited by the sine wave signal output from the function circuit 3, and the induced voltage signal SIN (θ _o − from the secondary winding whose phase with respect to the excited sine wave signal changes according to the rotational position θ _r
θ _r ) is output. The filter circuit 5 removes noise and distortion components from the output of the synchro electric machine 4, and inputs the output to the comparator circuit 6. The comparator circuit 6 outputs a square wave that changes at the zero point of the sine wave of the induced voltage signal, and the relationship of the expression (1) is established at the rising time.

θ _o −θ _r = 2nπ where n is an integer (1) Therefore, at the rising edge of the comparator circuit 6,
If the count value θ _o of the counter circuit 2 is latched, the relationship of equation (2) is established.

θ _o = 2nπ + θ _r (2) If the value of the count value θ _o of the counter circuit 2 which is equal to or greater than 2π is ignored as an overflow, the relationship of the expression (3) is satisfied.

θ _o = θ _r (3) A falling trigger D-type flip-flop circuit 7 is used to latch the count value θ _o of the counter circuit 2 which is always counting at a good timing. The output of the comparator circuit 6 is connected to the data input D of the flip-flop circuit 7, and the output of the clock generation circuit 1 is connected to the clock input CK. The data input D is sampled at the falling edge of the clock pulse, and the flip-flop circuit 7 outputs a square wave whose changing point is synchronized with the falling edge of the clock pulse. When the output of the flip-flop circuit 7 is used as the clock input of the latch circuit 7, the count value θ _o of the counter circuit 2 changes at the rising _edge of the clock pulse, so that the count value θ _o can be correctly latched.

In this way, the rotational position θ _r can be detected as a digital value by the value latched by the latch circuit 8.

(Problems to be Solved by the Invention) The phase detection converter has a simple circuit configuration, and most of it is a digital circuit, so that it can be inexpensive. However, the detected value is updated only at each zero point of the secondary induced voltage of the synchro electric machine, and the rotational position at an arbitrary time cannot be detected as in the tracking converter. In the control of the AC motor, it is necessary to control the time and the AC voltage or current according to the rotation of the motor, and the phase detection converter cannot be applied to such an application. Further, when the rotational position changes, the detection cycle changes depending on the rotational speed. Therefore, it is difficult to apply this method to the digital control of the electric motor because it cannot be synchronized with the sampling of the digital control.

The present invention has been made in view of the above circumstances, and while utilizing the advantage in the circuit configuration of the phase detection type converter, solves the disadvantage that only intermittent detection is possible, and uses a synchro electric machine suitable for control of an AC motor or digital control. The purpose is to obtain a rotation detection device.

[Structure of Invention]

(Means for Solving Problems) The outline of the present invention will be described with reference to FIG. An excitation circuit for generating an AC excitation signal, which includes a clock generation circuit 1, a counter circuit 2, and a function circuit 3, and a synchro electric machine 4 that has a multiphase primary winding and a secondary winding and is coupled to a rotating body, Filter circuit 5, comparator circuit 6, flip-flop circuit 7,
A phase difference detection circuit configured to include a latch circuit 9 and a counter circuit 10 for detecting a phase difference and its detection time, and a latch circuit 1.
2,13,14,16, a predictive arithmetic circuit including a flip-flop circuit 7 and an arithmetic unit 15, and a rate multiplier circuit 17
And an up-down counter circuit 18.

(Operation) When the multiphase primary winding of the synchronous electric machine is excited by the AC excitation signal output from the exciting circuit, an induced voltage signal whose phase changes according to the rotational position is generated in the secondary winding. The zero point of the induced voltage signal is detected by the filter circuit 5, the comparator circuit 6, and the flip-flop circuit 7, and the count value of the counter circuit 2 indicating the phase of the alternating-current excitation signal at that time is latched by the latch circuit 9 to change the phase. Is detected by the phase difference detection circuit as a phase difference between the AC excitation signal and the induced voltage signal. At this time, the count value of the higher-order counter circuit 10 of the counter circuit 2 is also latched so that the latch circuit 9 detects not only the phase difference but also the time. At the same time, the phase difference and its detection time before that are transferred to the latch circuit 11 of the predictive calculation circuit.The predictive calculation circuit uses these data to calculate the predicted rotational position at the time of every fixed cycle, and The change amount of the predicted rotational position is calculated and the rate input of the rate multiplier circuit 17 is set. The rate multiplier circuit 17 outputs a pulse having a frequency corresponding to the rate input, and the up / down counter circuit 18 counts the pulse.
The count value of the up / down counter circuit 18 follows the predicted rotation position, and the time of this tracking delay and the advance time by the prediction calculation are offset, and the rotation position is detected as a digital value with almost no delay by the count value of the up / down counter circuit 18. it can.

(Example) (Structure of Example) An example of the present invention in FIG. 1 will be described. 1 is a clock generation circuit, 2 is a counter circuit, 3 is a function circuit, 4 is a synchro electric machine (resolver), 5 is a filter circuit, 6 is a comparator circuit, and 7 is a flip-flop circuit, which is the same as the conventional example. 9,11,12,13,14,16 are latch circuits, 12,13,1
The 4, 16 latch circuits are 3-state output type which can control the output. 10 is a counter circuit, 15 is a microcomputer as an arithmetic unit, 17 is a rate multiplier circuit, 18
Is an up-down counter circuit.

(Operation of Embodiment) The clock pulse output from the clock generation circuit 1 is counted by the counter circuit 2, and the count value θ _o increases with time. The count value theta _o is inputted to the function circuit 3, a total count theta _o 2-phase sine wave signal SIN _o corresponding to, COS .theta _o it is output. The synchro electric machine (resolver) 4 is excited by the two-phase sine wave signal output from the function circuit 3, and the induced voltage signal from the secondary winding whose phase with respect to the excited sine wave signal changes according to the rotational position θ _r. SIN (θ _o −θ _r ) is output. The output from the synchro electric machine 4 is converted into a square wave that changes at the zero point of the induced voltage signal through the comparator circuit 6 and the flip-flop circuit 7 by removing noise and distortion components by the filter circuit 6 as in the conventional example. It At the time of rising of this square wave, the count value θ _o of the counter circuit 2 is latched by the latch circuit 9, and the rotational position θ _r is detected as the phase difference between the excitation signal and the induced voltage signal. At this time, the count value θ _h of the upper counter 10 of the counter circuit 2 is also latched in the same latch circuit 9 as t _h . Combined data t of the data t _h and lower data theta _r higher latched by the latch circuit _{9 (= t h · θ r} ) will indicate the time at which the rotational position theta _r was detected. At the same time, the previous rotational position latched in the latch circuit 9 and its detection time data are transferred. Therefore, the latest rotation position and its detection time data t _NEW (= t _hNEW · θ) are always stored in the latch circuit 9.
_rNEW ) is latched, and the previous rotation position and its detection time data t _OLD (= t _hOLD · θ _rOLD ) are latched in the latch circuit 11.
Is latched. At the rising edge of the carry output C of the counter circuit 2 that is output at the same cycle of the excitation cycle, the latest rotational position at that time and the detected time data t
_NEW (= t _hNEW · θ _rNEW ) is from latch circuit 9 to latch circuit
The data is transferred to 13 and the previous rotational position and its detection time data t _OLD (= t _hOLD · θ _rOLD ) are transferred from the latch circuit 11 to the latch circuit 14. Further, the count value θ _h of the counter circuit 10 at that time is simultaneously latched in the latch circuit 12 as time data t _hSYN . It is necessary to simultaneously latch the count value θ _o of the counter circuit 2 as lower data of the time data t _hSYN , but the count value θ _o is 0 immediately after the carry output is issued.
Therefore, it is omitted. These latch circuits are provided because the microcomputer 15 cannot read data at the same time.

The microcomputer 15 checks the data change in the latch circuit 12, and if there is a change, sequentially reads these data and performs a prediction calculation. FIG. 2 shows the principle of predictive calculation of the rotational position. The horizontal axis represents time t, and the vertical axis represents the rotational position θ _r . The latest rotational position data latched in the latch circuit 13 is θ _rNEW ,
The detection time data is t _NEW , the previous rotational position data latched by the latch circuit 14 is θ _rOLD , the detection time data is t _OLD , the time data latched by the latch circuit 12 is t _hSYN
Lower time data t of _ISYN is _set to 0
It is indicated by _SYN (= th _hSYN · 0). When the predicted rotational position θ _rD at the time t _D is predicted and calculated, as shown in the figure, from the previous rotational position θ _rOLD and its detection time t _OLD, and the latest rotational position θ _rNEW and its detection time t _NEW , Obtained by linear approximation. This prediction calculation is expressed by an equation (4).

θ _rD = {(θ _rNEW −θ _rOLD ) × (t _D −t _NEW ) / (t _NEW −t _OLD )} + θ _rNEW (4) Time t _OUT is the time required for the prediction calculation of the microcomputer 15 τ _CPU and Considering the tracking delay time τ _DLY of the up-down counter circuit 18, the equation (5) is used.

t _D = t _SYN + τ _CPU + τ _DLY (5) These prediction operations are repeatedly executed each time the data in the latch circuit 12 changes, that is, in synchronization with the excitation cycle. From the previous rotational position θ _rOLD2 and its detection time t _OLD2, and the previous rotational position θ _rOOD and its detection time t _OLD , the time t
The predicted rotational position θ _{rD2 at C} (t _D2 ) is similarly obtained. Therefore, the time from time t _C to time t _D τ _DLY
Is equal to the excitation period, and the change in predicted rotational position during this period Δθ
_rD is given by equation (6).

Δθ _rD = θ _rD −θ _rD2 (6) The microcomputer 15 _executes the predictive calculation of formulas (5) and (4) and the predictive rotational position change calculation of formula (6),
Absolute value of predicted rotational position change Δθ _rD at time t _C | Δθ
_rD | is output to the rate input of the rate multiplier circuit 17, and the sign SIGN is output to the up / down counter circuit 18
Output to up / down input U / D of. From the rate multiplier circuit 17, a number of pulses equal to the absolute value | Δθ _rD | given as the rate input are output at substantially equal intervals during the time τ _DLY . This pulse is input to the clock of the up / down counter circuit 18, and its count value θ _rC
Increases or decreases according to the sign SIGN given to the up / down input U / D. Equal count theta _rC at time t _C is the predicted rotational position theta _RD2 one time before, the count value theta _rC coincide at time t _D to the predicted rotational position theta _rD.

Thereafter, by the similar operation, the predicted rotational position and the count value θ _rC of the up / down counter circuit 18 match at every period equal to the excitation period, and during that period, they change substantially linearly as shown in FIG. . The latch circuit 16 is provided to match the initial value of the _count value θ _rC of the up / down counter circuit 18. In the initial state, the microcomputer 15
_{Reads the} count value θ _rC of the up / down counter circuit 18 via the latch circuit 16 and operates the rate input of the rate multiplier circuit 17 so that the detected values of the rotational position match.

According to the embodiment of the present invention described above, the count value of the up / down counter circuit 18 follows the rotational position with almost no delay, and the rotational position can be continuously obtained as a digital value.

In the embodiment, the prediction calculation is obtained by linear approximation from two rotation positions and their detection times, but may be obtained by curve approximation from three or more rotation positions and their detection times. Further, the calculation circuit does not need to match the calculation cycle with the excitation cycle, and an arbitrary cycle is possible.

Needless to say, even if the present invention is applied to a linear synchro electric machine, similar effects can be obtained as a straight line detecting device.

〔The invention's effect〕

According to the present invention, the limitation of the detection cycle, which is a defect of the conventional rotation detection device that combines the synchro electric machine and the phase detection converter, is eliminated, and continuous detection is possible. It is possible to detect at an arbitrary time and to detect at a fixed cycle. Therefore, it is possible to easily generate a continuous command value of the AC voltage or current in the control of the AC motor based on the rotational position detected by the rotation detection device of the present invention. Further, even when the rotation detecting device of the present invention is used for digital control of the electric motor, it is possible to easily synchronize the control sampling period with the detection period. Moreover, most of the circuit configuration is a digital circuit, which can be integrated into a circuit, and can be made small and inexpensive.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a diagram for explaining the present invention, and FIG. 3 is a block diagram showing a conventional device. 1 ... Clock generator circuit 2,10 ... Counter circuit, 3 ... Function generator circuit 4 ... Synchronizer (resolver) 5 ... Filter circuit, 6 ... Comparator circuit 7 ... Flip-flop circuit 8,9,10 , 11,12,13,14,16 …… Latch circuit 15 …… Computer (microcomputer) 17 …… Rate multiplier circuit 18 …… Up-down counter circuit

Claims (1)

[Claims] 1. An exciting circuit for generating a multi-phase alternating current excitation signal, and an angle proportional to a rotational position of the rotary body coupled to a rotating body, wherein a multi-phase primary winding is excited by the alternating current exciting signal. A synchro electric machine that generates an induced voltage signal whose phase changes only by a secondary winding, a phase difference detection circuit that detects a phase difference between the AC excitation signal and the induced voltage signal and a detection time thereof, and the phase difference detection. A predictive arithmetic circuit that predicts the rotational position of the rotating body at a time of a constant cycle from two or more phase differences detected by the circuit and its detection time, and a change amount of the rotational position predicted by the predictive arithmetic circuit are set. Rate multiplier circuit and an up-down counter circuit that counts the output of the rate multiplier circuit, and the output of the up-down counter circuit is at the rotational position. URN to be equal, the rotation detecting device using a synchronous electrical machine, characterized in that the time the output is taken into consideration the time to follow the up-down counter circuit the time for predicting a rotational position in said predictive computation circuit.