JPH0427799B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field This invention relates to a PWM control device for controlling the speed of a motor. Prior Art Conventionally, this type of PWM control device realizes PWM by comparing a triangular wave or a sawtooth wave with an analog command signal. Therefore, it is necessary to use a DA converter that performs DA conversion of the digital command signal, and as a result, there is a problem in that circuit measures such as drift correction are required and the number of parts increases. Furthermore, since a triangular wave or sawtooth wave and an analog signal are used, it is not easy to programmably change the PWA frequency and servo gain. Purpose This invention was made to solve the above problems, and its purpose is to eliminate the need for adjusting the analog part by not using a triangular wave or a sawtooth wave, and to make it programmable with simple adjustment.
The present invention provides a PWM control device for controlling the speed of a motor that can change the PWM frequency and servo gain. Embodiment Hereinafter, an embodiment in which the present invention is embodied in a pattern sewing machine will be described with reference to the drawings. As shown in FIG. 1, a sewing machine main body 1 is mounted on a sewing machine table 2, and a sewing machine motor (DC motor) 3 for driving a main shaft of the sewing machine inside the sewing machine main body 1 is mounted on one side thereof. A needle bar 5, which is operatively connected to the main shaft of the sewing machine, is mounted on the head 4a of the bracket arm 4 of the sewing machine main body 1 so as to be movable up and down. driven object. The sewing machine table 2 corresponds to the sewing needle 5a of the needle bar 5.
A ring-shaped work cloth holding frame 6 for holding a work cloth K is provided above, and constitutes a driven object of an X-axis pulse motor and a Y-axis pulse motor (both not shown). The work cloth holding frame 6 moves horizontally on the sewing machine table 2 by the rotation of the X-axis pulse motor.
It is also provided so as to be moved back and forth on the sewing machine table 2 by rotation of the Y-axis pulse motor. Next, a control device for a sewing machine configured as described above will be explained. The control device is built in a control box 7 provided on the lower front surface of the sewing machine table 2 in FIG. A stop key 10 that outputs a stop signal SGSP for making an emergency stop of the sewing machine 1, and four jog keys 11 that output a position setting signal SGPO for setting the position of the work cloth holding frame 6 are provided. . The sewing machine motor 3 is provided with a position detector 13, so that 200 sinusoidal position signals SGM are output for one revolution of the motor. Similar position detectors are also provided for the X-axis and Y-axis pulse motors, and position signals SGX and SGY are output from each detector, respectively. In FIG. 2, waveform shaping circuits 14, 15, 16 and multiplier circuits 17, 18, 1 forming the detection circuit are shown.
9 and counter circuits 20, 21, etc. detect the rotational positions of the sewing machine motor 3, X-axis, and Y-axis pulse motors at any given time as digital signals based on the position signals SGM, SGX, and SGY. The waveform shaping circuits 14, 15, and 16 transform the sinusoidal position signals SGX, SGY, and SGM into rectangular position signals, respectively.
The waveforms are shaped into SGXa, SGYa, and SGMa, and output to the next-stage multiplier circuits 17, 18, and 19. Further, each waveform shaping circuit 14, 15, 16 receives a position signal whose phase is shifted by 90 degrees with respect to the sinusoidal position signals SGX, SGY, SGM, and converts them into rectangular wave position signals SGXa, SGYa, SGMa. The signal is shaped into a waveform and output to the next-stage multiplier circuits 17, 18, and 19. Multiplier circuits 17, 18, 19 respectively receive corresponding position signals SGXa, SGXb, SGYa, SGYb,
SGMa and SGMb are input, and based on the phase difference between these two signals, it is determined whether the motor is in forward or reverse direction. If the motor is rotating in the normal direction, the normal rotation position signal is generated by multiplying the position signal by four times. SGXP, SGYP,
When the SGMP is reversed, the reverse position signal is also obtained by multiplying the position signal by 4 times.
Output SGXN, SGYN, SGMN. The two counter circuits 20 and 21 are each composed of three counters, and each counter has the normal rotation,
Reverse position signal SGXP, SGYP, SGMP, SGXN,
Digitally count SGYN and SGMN,
Its count value ECDNX, ECDPX, ECDNY,
The rotational position of each motor is calculated based on ECDPY, ECDND, and ECDPD. Further, the waveform shaping circuit 16 corresponding to the sewing machine motor 3 outputs an origin signal PG (a signal output when the tip of the sewing needle 5a escapes upward from the workpiece cloth K) based on the position signal SGM. This origin signal PG is the input port 2 that inputs the signals SGS, SGSP, and SGPO of each key such as the start key 9.
2 and is input to the flip-flop circuit 23. The flip-flop circuit 23 then uses this origin signal.
The synchronization signal SGSY is input to the same input port 2 based on PG.
Output to 2. A central processing unit (hereinafter referred to as CPU) 24 as a calculation means includes a read-only memory (hereinafter referred to as ROM) 25 that includes each register as a storage means.
The timing signal is configured to operate according to a control program stored in the input port 22, and receives each of the signals inputted to the input port 22, and is outputted at a constant period (350 μsec) to be described later.
Enter SGT. Then, each time the CPU 24 inputs this timing signal SGT, the count value of each counter of the counter circuits 20 and 21 is calculated.
ECDNX, ECDPX, ECDNY, ECDPY,
Read ECDND, ECDPD, sewing machine motor 3
Find the rotational position of each motor, etc., and calculate the rotational speed of each motor when the timing signal SGT is generated.
Calculate Vd, Vx, Vy, rotational acceleration αd, αx, αy, etc. Readable and rewritable memory (hereinafter referred to as
A RAM 26 stores pattern data as a speed command signal for commanding the amount of rotation of each motor such as the sewing machine motor 3 for pattern sewing to be applied to the work cloth K. As shown in Figure 3, the pattern data includes a start code COST to start sewing and an end code COEN to end sewing, which are stored at the beginning and end. Rotation amount data fdx, fdy of the X-axis and Y-axis pulse motors for moving the work cloth holding frame 6 in the X direction and the Y direction,
Data fdd of the amount of rotation of the sewing machine motor 3 for each stitch (in this embodiment, the amount of rotation is constant from beginning to end) is stored in accordance with the sewing order. Then, the CPU 24 receives the timing signal SGT.
Each time you input the rotation amount data fdx,
Deviation εd between fdy, fdd and rotational speed Vd, Xx, Vy,
Calculate εx, εy and calculate their deviations εd, εx, εy
The rotational speed Vd, Vx, Vy and the rotational speed αd,
Calculate the feedback of αx and αy to calculate the deviation amount.
PWMAD, PWMBD, PWMAX, PWMBX,
It is designed to calculate PWMAY, PWMBY, etc. The three pulse generating circuits 27, 28, and 29 as pulse generating means provided corresponding to each motor such as the sewing machine motor 3 each have three programmable interval timers each having a preset type 16-bit counter, two of which are Trigger signal TG for supplying drive current to the motor
and pulse signals SGXPP, SGXPN, SGYPP, SGYPN, which are output based on the clock signal CK.
Counters 27a, 27b to 29 that output SGMDP and SGMDN by changing their duty ratios
a, 29b, and the other one is used as a clock signal generation circuit (frequency dividing circuit) 27c, 28, respectively.
c, 29c. Counter 27a~
29b is loaded with the deviation amount from the CPU 24, and each time the trigger signal TG is input, the deviation amount is sequentially counted down by the falling edge of the clock signal CK, and when the value reaches zero, it becomes a positive potential (hereinafter referred to as Outputs a pulse signal (H level). Clock signal CK is a pulse oscillator (not shown)
The 2MHz pulse signal _SGP1 output from the Y-axis pulse motor is divided into 400KHz by the clock signal generation circuit 28c of the pulse generation circuit 28 corresponding to the Y-axis pulse motor, and is output to each of the counters 27a to 29b. The trigger signal TG converts the clock signal CK into a pulse generating circuit 27 corresponding to the X-axis pulse motor.
The clock signal circuit 27C divides the frequency into 6KHz and outputs it to each of the counters 27a to 29b. Further, in this embodiment, the clock signal generating circuit 29c of the pulse generating circuit 29 provided corresponding to the sewing machine motor 3 is used as a timing signal generating circuit for outputting the timing signal SGT, which is output from a pulse oscillator (not shown). 154KHz
Pulse signal SGP ₂ 2.8KHz timing signal
The frequency is divided into SGT and output to the CPU 24. Next, a switching circuit that supplies drive current to each motor based on the pulse signals SGXPP to SGMDN output from the pulse generation circuits 27 to 29 will be described. Note that each switching circuit has the same circuit configuration, so
The switching circuit of the sewing machine motor 3 will be explained using the same reference numerals. The pulse signal SGMDP of the counter 29a of the pulse generating circuit 29 is sent to the not circuits 30, 31 and the delay circuit 3.
2 and a NAND circuit 3 via a Schmitt circuit 33.
4, and is also output to an AND circuit 37 via a NOT circuit 30, a delay circuit 35, and a Schmitt circuit 36. Further, the pulse signal SGMDN of the counter 29b is output to the AND circuit 42 via the NOT circuits 38, 39, the delay circuit 40, and the Schmitt circuit 41, and is also output to the NOT circuit 3.
8, is outputted to a NAND circuit 45 via a delay circuit 43 and a Schmitt circuit 44. Then, when an H level output signal is output from the delay circuits 35 and 43, the switching transistor Q ₁ of the drive circuit 46 serving as a switching circuit
Of the transistors Q ₁ and Q ₄ , transistors Q 1 and Q ₄ are turned on, a drive current is supplied to the sewing machine motor 3, and the motor 3 is driven in normal rotation. The AND circuits 37, 42 and the NAND circuits 34, 35 are configured to receive a current limiting signal outputted from the drive circuit 46 and a stop signal SGSV for emergency stop of the sewing machine. In addition, the control device of this sewing machine is input/output port 4.
It can be connected to a personal computer via the input/output port 49 and the level converter 50, making it possible to transfer data and control operations from the personal computer.
The machine is connected to the control device of other sewing machines via the machine, so that the machines can control each other's operations. Next, the operation of the control device configured as described above will be explained with reference to a flowchart showing the operation of the CPU 24. First, as shown in FIG. 1, the work cloth K is held by the work cloth holding frame 6 on the sewing machine table 2. When the power switch (not shown) is turned on in this state, the CPU 24 clears each register in the CPU 24 and also clears the counter circuits 20 and 2.
1 and the pulse generation circuits 27 to 29 are initialized. Next, the CPU 24 reads the pattern data from the RAM 26, and moves the drive shaft of each motor such as the sewing machine motor 3 to a predetermined origin position (in the case of the sewing machine motor 3, to a position where the sewing needle 5a exits upward from the workpiece cloth K). After returning to the corresponding rotation position), it waits for the start key 9 to be operated. Start key 9 is pressed and start signal SGST
is input to the CPU 24, the CPU 24 inputs the rotation amount data fdd of the sewing machine motor 3 to the CPU 24.
The data is input to the FDD register and the sewing machine motor 3 is driven based on this data. When the synchronizing signal SGSY is reversed, that is, when the sewing needle 5a descends from the needle top position to the needle bottom position and comes out of the work cloth K again, the second stitch In order to guide the workpiece cloth K to the sewing position, the rotation amount data fdx and fdy of the X-axis and Y-axis pulse motors are input into the FDX register and FDY register of the CPU 24, respectively, and the rotation amount data fdd of the sewing machine motor 3 for the second stitch is input. Input to FDD register. Therefore, based on the rotation amount data fdx, fdy, the X-axis and Y-axis pulse motors rotate, and the work cloth K is moved to a predetermined position via the holding frame 6. Based on the rotation amount data fdd, The sewing machine motor 3 rotates, and the sewing needle 5a moves downward and upward in one cycle, thereby sewing the second stitch. During this time, the CPU 24 counts the number of stitches with its stitch counter, determines whether the data at the next address of the pattern data is the end code COEN, and waits for the synchronization signal SGSY to be inverted. Then, every time the synchronization signal SGSY is inverted,
In other words, each time each stitch is finished,
Rotation amount data for forming the next seam in the same way as above
The fdx, fdy, and fdd are read and sewing is performed based on the same data. And finally the exit code
When COEN is read out, the sewing of the work cloth K is completed and the sewing of the next work cloth K is awaited. Next, the rotation control of each motor for each stitch will be explained in detail based on the rotation amount data fdx, fdy, and fdd for each stitch during the sewing operation. The CPU 24 receives a clock signal from a clock signal generating circuit 29c, which is used as a timing signal generating circuit for the pulse generating circuit 29, while the synchronizing signal SGSY is inverted, that is, when one stitch sewing cycle is completed.
The timing signal SGT, which is output every 350 μs, is input as an interrupt signal. Further, the counters of the counter circuits 20 and 21 sequentially digitally count the rotational position of each motor such as the sewing machine motor 3, and each pulse generating circuit 27
~29 counters 27a, 27b ~ 29a, 2
A 400KHz clock signal CK and a 6KHz trigger signal TG are input to 9b. Now, when the synchronization signal SGSY is inverted and the first timing signal SGT is input to the CPU 24 with each rotation amount data fdx, fdy, fdd input to each register, the CPU 24 receives the X-axis pulse motor from the counter circuit 20. Count value for forward and reverse rotation of
Read ECDPX and ECDNX and find the rotational position θx of the drive shaft in the same motor (=ECDNX - ECDPX)
seek. Next, the CPU 24 determines the current rotational speed Vx (=θx−θx _{0 ) of the X-axis motor from the previous rotational position θx 0 ,} which was previously determined in the same manner as above and temporarily stored in the θx 0 register of the CPU ₂₄ . At the same time, this rotational position θx is stored in the θx ₀ register as data of the new previous rotational position θx ₀ . When the rotational speed Vx is determined, the CPU 24 uses this speed Vx
is obtained in the same way as above, and Vx ₀ of CPU24
Destination rotation speed Vx ₀ temporarily stored in register
The rotational acceleration αx (=Vx−Vx ₀ ) at that time is calculated from the above, and this rotational speed Vx is stored in the Vx ₀ register as data of the new previous rotational speed Vx ₀ . When calculating the rotational acceleration αx, the CPU 24 calculates this acceleration αx and the same method as above,
_{Acceleration increment} △αx (=αx
−αx ₀ ), and the acceleration αx is stored in the αx ₀ register as new data of the previous rotational acceleration αx ₀ . The CPU 24 uses the above calculated value and the previous timing signal.
The deviation εx (=εx ₀ −Vx−k1αxk2Δαx, k1, k2 are predetermined proportionality constants) is calculated from the deviation εx _0, which will be described later, obtained by SGT. Then the CPU
24 determines whether there is rotation amount data fdx in the FDX register, then subtracts the same data fdx by a predetermined unit rotation amount △fdx to be described later, and the subtracted value (= fdx − △fdx) is new. rotation amount data
Store it in the FDX register as fdx. In addition,
The unit rotation amount △fdx is a digital value to be calculated as a rotation command every time the timing signal SGT is output, and is set in advance corresponding to the rotation amount data fdx for each sewing cycle.
It is stored in the RAM 26 together with the data fdx, read out together with the same data fdx, and input into the ΔFDX register. Note that in this embodiment, all values are set to constant values. Next, the CPU 24 adds the calculated deviation εx and the unit rotation amount △fdx, stores the added value as a new deviation εx ₀ (=εx+△fdx) in the εx ₀ register, and also adds the deviation amount PWMAX ( =εx ₀ +
PWS) and PWMBX (PWS-εx ₀ ) are calculated and loaded into each counter 27a, 27b of the pulse generation circuit 27. Here PWS is 6KHz trigger signal TG
is output and the number of 400KHz clock signals CK (≒66) that are output while the next trigger signal TG is output is set to 1/2 (=33). Deviation amount PWMAX in pulse generation circuit 27,
When PWMBX is loaded, the CPU 24 performs the same processing operation as above, calculates the deviation amounts PWMAY and PWMBY for the Y-axis pulse motor, loads them into the pulse generation circuit 28, and calculates the deviation amounts PWMAD and PWMBD for the sewing machine motor. The pulse generation circuit 29 is loaded. Counters 27a and 27b of pulse generation circuit 27
The trigger signal TG is input to the deviation amount PWMAX,
When PWMBX is loaded, each counter 27a,
27b sets its output signals SGXPP and SGXPN to L level, and also sets the deviation amount PWMAX,
PWMBX is counted down every time the clock signal CK is input. When the PWMBX clock signal CK is input, the counter 27b becomes 0 and outputs an H level pulse signal SGXPN. Drive current is supplied to the X-axis pulse motor by the H-level pulse signal SGXPN and the L-level output signal SGXPP, and the pulse motor is driven to rotate in the forward direction. Then, PWMAX clock signal CK
When the counter 27a is inputted, the counter 27a becomes 0 and outputs the H level pulse signal SGXPP. When both pulse signals SGXPP and SGXPN become H level, the supply of drive current to the X-axis pulse motor is stopped. In other words, the deviation amount calculated by the CPU 24
The drive current for normal rotation drive is time-controlled based on pulse signals SGXPP and SGXPN, which have a duty ratio proportional to PWMAX and PWMBX.
Supplied to the shaft pulse motor. And Y-axis pulse motor and sewing machine motor 3
The drive current supply is controlled in the same way. When the next timing signal SGT is input to the CPU 24, the CPU 24 again performs the same arithmetic processing operation as described above. First, the CPU 24 is the counter circuit 2
Read count values ECDPX and ECDNX from 0,
The rotational position θx of the drive shaft of the X-axis pulse motor at that time is determined, and based on this rotational position θx, the rotational speed Vx (=θx−θx ₀ ) and rotational acceleration αx (=
Vx − Vx ₀ ) and acceleration increment △αx (= αx − αx ₀ ), and each calculated value θx, Vx, αx
are stored in each register as new values θx ₀ , Vx ₀ , αx ₀ . Next, the CPU 24 calculates the current deviation εx (=εx ₀ −Vx−k1αx−k2Δαx) from the previous deviation εx ₀ previously stored in the εx ₀ register and these new values Vx, αx, Δαx, A new deviation εx ₀ (=εx+Δfdx) is obtained by adding the unit rotation amount Δfxd to the obtained deviation εx.
Then, the CPU 24 generates a new deviation amount PWMAX (=
εx ₀ +PWS) and PWMBX (=PWS−εx ₀ ) are calculated, and each counter 27a, 2 of the pulse generation circuit 27
7b. Each counter 27a, 27b counts down the loaded deviation amounts PWMAX, PWMBX based on the clock signal CK in response to the trigger signal TG, and the supply of drive current to the X-axis pulse motor is time-controlled. Similarly Y
The supply of drive current to the shaft pulse motor and the sewing machine motor 3 is controlled in the same manner. From then on, rotation amount data fdx is generated every time the timing signal SGT is output until the synchronization signal SGSY is inverted.
is read out for each unit rotation amount Δfdx, the same calculation as above is performed, and the drive current is time-controlled at each time, that is, every 350 μs. In this way, in this embodiment, until the synchronization signal SGSY is inverted, the rotation amount data fdx in that cycle is not all subject to calculation as a rotation command at once, but the timing signal
Each time SGT is output, the unit rotation amount △fdx is subtracted from the same rotation amount data fdx, and the unit rotation amount △fdx is used as the calculation target, and the rotation speed Vx, rotation acceleration αx, and acceleration increment △αx at that time are calculated. Each time a timing signal is input, each value is accumulated, and a deviation εx is obtained from each accumulated value and the rotational speed Vx, rotational acceleration αx, and acceleration increment Δαx at that time. Then, based on this deviation εx, the deviation amount PWMAX at that time,
Find PWMBX and control the drive current supply. Therefore, until the synchronization signal SGSY is inverted, the supply of drive current is controlled so as to respond to the current rotation command determined according to the change in the rotational speed Vx and rotational acceleration αx. Therefore, the rotation of the motor can be controlled efficiently and accurately. Incidentally, as a result of experiments on the sewing machine motor 3, the results shown in Table 1 were obtained. As a result, rotation amount data fdd (=1000), unit rotation amount △fdd (=100)
It can be seen that the sewing machine motor 3 quickly reaches the amount of rotation based on . Furthermore, simply by changing the period of the timing signal SGT, the servo gain can be changed, and the trigger signal TG and clock signal CK can also be easily varied, so motor control can be adjusted programmably. In the above embodiment, the actual speed was detected as a digital value, but it may be detected as an analog value and converted to a digital value at the stage of determining the deviation amount.

[Table] Effects As described above, the present invention calculates the amount of deviation between the speed command signal and the actual rotational speed as digital data, and uses the pulse train generation means to conduct or interrupt the drive current of the motor based on the calculated data. Since the duty ratio of the pulse train to be generated is variable, there is no need for a triangular wave generation circuit, and
The pulse train generating means is built in the CPU,
Alternatively, it can be configured by reusing a timer IC installed for other purposes, which not only simplifies the configuration, but also improves reliability, and allows programmable PWM frequency and servo gain with easy adjustment. can be changed.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a sewing machine embodying the present invention, Fig. 2 is an electric block circuit diagram of the digital servo control device of the sewing machine, Fig. 3 is a diagram showing the contents of pattern data, and Fig. 4 is a pulse generation circuit. 5 to 9 are flowcharts explaining the operation of the CPU. Sewing machine motor...3, Position detector...13, Counter circuit...20, 21, Central processing unit (CPU)...24, Pulse generator circuit...27,2
8, 29, drive circuit...46.

Claims (1)

[Claims] 1. A speed command signal fdd, etc. for commanding the rotational speed of the motor 3, etc., and a rotational speed signal Vd, etc. from the detection circuits 20, 21, etc. that detect the actual rotational speed of the motor 3, etc. In motor speed control, the motor 3, etc. is supplied with a current according to the deviation amount PWMAD, etc. related to the timing, and rotates the motor 3, etc. at a desired rotation speed based on the speed command signal, fdd, etc. A timing signal generation circuit 29c that generates a signal SGT, a trigger signal generation circuit 27c that generates a trigger signal TG having a cycle shorter than the cycle of the timing signal SGT, and a clock having a cycle shorter than the cycle of the trigger signal TG. a clock signal generation circuit 28c that generates a signal CK; and a clock signal generation circuit 28c that generates a signal CK, and each time the timing signal SGT is generated, the deviation amount PWMAD, etc. calculated due to the previous generation of the timing signal SGT is calculated according to the rotational speed signal Vd, etc. to correct the new deviation amount.
a calculation means 24 for calculating PWMAD, etc. as digital data; and counting the number of occurrences of the clock signal CK each time the output is inverted in relation to the generation of the timing signal SGT and the trigger signal TG is generated; pulse train generating means 27 for generating a pulse train having a duty ratio associated with the digital data such as the deviation amount PWMAD by inverting the number again when the number reaches a predetermined value corresponding to the calculation result of the calculating means 24; , 28, 29, and a switching circuit 46 that conducts and cuts off the supply current to the motor 3 etc. based on the pulse train from the pulse train generating means 27, 28, 29. PWM control device in. 2 The speed command signal fdd, etc. and rotational speed signal Vd
etc. are both expressed as digital quantities, and the calculation means 24 calculates the timing signal SGT.
occurs, the first storage means 24 for temporarily storing the speed command signal fdd, etc. and the rotational speed signal Vd, etc. expressed in digital quantities and the calculation results calculated by the calculation means 24 are temporarily stored. 2nd to memorize
The pulse train generating means 27, 28, 29 load the calculation results of the deviation amount PWMAD etc. stored in the second storage means 24 as digital data in response to the trigger TG, and The counters 27a, 27b, etc. count the calculation results of the clock signal CK, which are also calculated as digital data, from the calculation results of the deviation amount PWMAD, etc., and change and control the duty ratio of each pulse of the pulse train based on the counting results. A PWM control device for controlling the speed of a motor according to claim 1. 3. The calculation means 24 is constituted by an interrupt-enabled microcomputer, the timing signal SGT from the timing signal generation circuit 29c is supplied as an interrupt trigger signal for the microcomputer, and the pulse train generation means 27, 28, 29 are 2. The PWM control device for motor speed control according to claim 1, further comprising a programmable counter connected to the microcomputer and having a retriggerable one-shot mode.