JP4451428B2 - Two-phase stepping motor drive circuit - Google Patents

Description

  The present invention relates to a drive circuit for a two-phase stepping motor having two independent windings, and reduces the number of circuit components by using a single current control system, which was separately required for each winding. In addition, the control by the microcomputer can be easily and simplified.

Stepping motors are widely used for moving the moving parts of various devices, and are widely used in fields of use that make it easy to control and confirm the amount of movement in an open loop without using a position sensor. Yes. When stepping motors are classified by the number of phases, the two-phase stepping motors that are most frequently used at present are two-phase stepping motors, and there are unipolar and bipolar connections in the connection system, and each circuit of the drive unit The configuration is different.

FIG. 9 is a block diagram showing a configuration of a driving circuit of a unipolar-connected two-phase stepping motor that has been conventionally used. From the external pulse signal P, target electrical angles of the A phase and the B phase having a phase difference of 90 degrees are determined, and the current target value signal is generated by the current target value generation unit for each of the A phase and the B phase. Is generated.

On the other hand, currents flowing in the A-phase winding and the B-phase winding are converted into voltage signals by the current detection resistors RSA and RSB, and after passing through a filter, become current feedback value signals IFBA and IFBB.
A current feedback control calculation is performed using a difference (error signal) between the current target value signal and the current feedback value signal to generate a PWM command value signal. The PWM command value signal is compared with a triangular wave generated by the PWM carrier signal generation unit by a comparator to generate a PWM signal.
The generated PWM signal is further divided into complementary PWM signals of the A phase gate signal GA and the A bar phase gate signal GA bar in the A phase, and the B phase gate signal GB and the B bar phase gate signal GB bar in the B phase.
The power element is switched by the generated gate signal to control the current flowing through each phase winding. The motor rotates by changing the ratio of the current flowing through the A-phase winding and the B-phase winding in accordance with the external pulse signal.
JP 07-194194 A

In the conventional drive circuit shown in FIG. 9, a current control system is configured for each of the A phase and the B phase. However, in the hardware control system using an operational amplifier, a comparator, etc., the time required for the control calculation is taken into consideration. There was no problem because it was not necessary. However, if the control system is to be applied to a software control method using a microcomputer, it is necessary to perform control calculations twice every control cycle, which is difficult to realize with a microcomputer having a low processing capacity. The actual motor current is an intermittent current under PWM control. The current flows from the power source + side through the motor winding to the power source-side, and from the power source-side through the motor winding to the power source + side. Therefore, when the current signal is used for control, filters 24-a and 24-b are required. When the filter is configured by hardware using an analog circuit, there is a problem that the number of parts of the driving circuit increases, and when the filter is configured by software of a microcomputer, there is a problem of increase in processing time.

In the present invention, in a unipolar connection or bipolar connection two-phase stepping motor driving circuit driven by a triangular wave comparison complementary PWM method, a single current detection resistor is required for performing current feedback control. The current control system is simplified by detecting the combined value of the currents flowing through all the windings and performing feedback control on the combined current value. In order to make the A-phase and B-phase current waveforms approach a sine wave during microstep driving, the current target value is varied according to the electrical angle. In addition, by changing the sampling timing of the A / D converter used when inputting the magnitude of the motor current to the microcomputer in accordance with the electrical angle, the power source + side is always changed to the power source-side at any electrical angle. Since the maximum value of the flowing current is detected, a filter is unnecessary for use in control.

In the drive circuit of the present invention, the current detection resistors for detecting current can be reduced from the conventional two to one, and the number of circuit components is reduced because a filter is not required. In addition, only one A / D converter may be used, and the current control system conventionally performs control computation separately for the A phase and the B phase, but only for one of the currents of the A phase and the B phase. Since the control is performed, the control calculation is simplified, and it can be realized even with an inexpensive microcomputer having a low processing capability.
Due to the above effects, the stepping motor drive circuit of the present invention can achieve downsizing and cost reduction compared to the conventional stepping motor drive circuit.

  This will be described with reference to the drawings.

FIG. 1 shows a system diagram of a drive circuit of a unipolar connection type two-phase stepping motor according to a first embodiment of the present invention, which is roughly composed of a control unit 1 and a drive unit 2-1.
The drive unit includes a winding 3 of a two-phase stepping motor having a unipolar connection, a semiconductor switching element group 4, and a current detection resistor 5. The winding 3 of the two-phase stepping motor of the unipolar connection has an A-phase winding composed of CA and CA bars, and a B-phase winding composed of CB and CB bars. Further, the CA winding and the CA bar winding are bifilar windings and are magnetically coupled. The same applies to the CB winding and the CB bar winding. One end of all the windings is connected to the power source + side, and the other end is connected to the drain terminals of the semiconductor switching elements SA, SA bar, SB, and SB bar for switching the respective windings. The source terminals of all the switching elements are connected to one end of the current detection resistor 5 and to the A / D conversion unit 17 of the control unit 1. The other end of the current detection resistor 5 is connected to the power supply side. The switching element SA is turned on / off by the gate signal GA output from the control unit 1, the switching element SA bar is turned on / off by the gate signal GA bar output from the control unit 1, and the switching element SB is turned on by the control unit. 1 is turned ON / OFF by a gate signal GB output from 1, and the switching element SB bar is turned ON / OFF by a gate signal GB bar output from the control unit 1.

FIG. 4 is a diagram illustrating a case where the switching of the A phase of the winding of the two-phase stepping motor of the unipolar connection is performed by the triangular wave comparison complementary PWM method. The following description will be given for the A phase, but the same applies to the B phase. SA and SA bar are in a complementary relationship. When SA is ON, SA bar is OFF, and when SA bar is ON, SA is OFF. Here, the triangular wave is standardized with a maximum value of 0 and a minimum value of 1. The triangular wave is always compared with the PWM switching timing value n. When the triangular wave size is larger than n, SA is ON and SA bar is OFF, and when smaller than n, SA is OFF and SA bar is ON. .
FIG. 4A shows SA, the ON / OFF state of the SA bar, and the sum IA of the current flowing through the CA winding and CA bar winding when n is 0.5. When n is 0.5, since the length of the SA ON period and the SA bar ON period are equal, almost no current flows due to the influence of the winding inductance.
FIG. 4-B shows SA / SA bar ON / OFF when n is smaller than 0.5, and the sum IA of the current flowing through the CA winding and CA bar winding. Since the SA ON period is longer than the SA bar ON period, the current flows from the power source + side through the CA winding to the power source-side in the SA bar ON period, and in the SA bar ON period, the current flows from the power source-side to the CA power source. It passes through the bar winding and regenerates to the power source + side. That is, the current flows from the power source + to the power source − on the mountain side of the triangular wave, and the current is regenerated from the power source − to the power source + on the valley side.
FIG. 4C shows the sum IA of SA and SA bar ON / OFF when the n is larger than 0.5 and the current flowing through the CA winding and CA bar winding. Since the SA bar ON period is longer than the SA ON period, in the SA bar ON period, current flows from the power source + side through the CA bar winding to the power source-side, and in the SA ON period, current flows from the power source-side. It passes through the CA winding and regenerates to the power source + side. That is, the current flows from the power source + to the power source − on the valley side of the triangular wave, and the current is regenerated from the power source − to the power source + on the mountain side.
Thus, in the triangular wave comparative complementary PMW system, when the PWM switching timing value n changes, the direction and period of current flow change.

FIG. 3 shows an internal block diagram of the control unit 1, and an electrical angle generation unit 9, a current target value generation unit 10, a control calculation unit 11, a phase generation unit 12, a PWM counter 13, and an A-phase switching timing generation. Unit 14-a, B phase switching timing generation unit 14-b, A phase comparator 15-a, B phase comparator 15-b, A phase complementary PWM signal generation unit 16-a, and B phase complementary PWM signal generation The A / D conversion unit 17 in the control unit includes an A / D sampling timing generation unit 18, a sampling timing comparator 19, a sampler 20, and an A / D converter 21. Consists of.

The electrical angle generation unit 9 receives a pulse signal P for instructing rotation of the motor and a rotation direction signal D for instructing the rotation direction from outside, and generates a pulse number TA corresponding to the A-phase electrical angle to generate a phase generation unit. 12, output to the target current value generator 10 and the A / D sampling timing generator 18. The electrical angle generator 9 is an UP / DOWN counter, which triggers the input of the pulse signal P, increments or decrements the counter value according to the logic level of the rotation direction signal D at this time, and outputs the counter value as TA. Since the angle for one pulse of the counter is a value obtained by dividing the electrical angle of 360 degrees by the unit step angle θs, the product of TA and θs is the electrical angle. The maximum value of the counter is equal to the number of steps for an electrical angle of 360 degrees. If it is a full step, the counter maximum value TAMAX is 4 and θs is 90 degrees. If it is a half step, TAMAX is 8 and θs is 45 degrees. If it is a step, TAMAX is 4 m and θs is 90 / m.

The current target value generation unit 10 receives the A-phase electrical angle output from the electrical angle generation unit 9, generates a current target value IREF, and outputs it to the control calculation unit 11. Here, the IREF outputs the winding current at the time of microstep driving close to a sine wave and after performing correction processing according to the value of TA in order to further reduce the vibration.
FIG. 5 explains the difference between the case where the current target value IREF is constant and the case where the current target value IREF is changed according to the A-phase electrical angle, for each winding current when the stepping motor of unipolar connection is driven in four divided microsteps. It is a figure to do.
FIG. 5-A shows the current waveform of each winding when the current target value IREF is a constant value. At this time, the winding current waveform is a stepped triangular wave. This is because feedback control is applied so that the combined current of the A phase and the B phase is always constant.
FIG. 5-B shows the current waveform of each winding when the current target value IREF is corrected by calculating the following equation. In this case, the current waveform can be made closer to a sine wave.
IREF = IREFMAX × sin (TA × θs−45 × (2d−3))
Here, IREFMAX is the maximum value of the current target value, d represents the quadrant number of the electrical angle (TA × θs), and if TA × θs is 0 degree or more and less than 90 degrees, d = 1, 90 degrees or more and 180 degrees. D = 2 if the angle is less than 180 degrees, d = 3 if 180 degrees or more and less than 270 degrees, and d = 4 if it is 270 degrees or more and less than 360 degrees.
FIG. 5 shows a waveform at the time of four-divided microstep drive. In this case, θs is 22.5 degrees. However, in the case of a microstep drive having a higher number of divisions, only the value of θs is reduced, and the current target is reduced. The concept of value correction is the same. Further, the regenerative current is omitted from each phase current waveform in FIG.

The control calculation unit 11 takes a difference between the current target value IREF generated by the current target value generation unit 10 and the current feedback value IFB converted into a digital signal by the A / D converter 21 and performs feedback control calculation. A PWM amplitude value AMP is generated and output. The PWM amplitude value AMP generated here is a value that determines the amplitude of the motor winding current. When the current feedback value IFB is smaller than the current target value IREF, the PWM amplitude value AMP increases, and conversely, the current target value. When the current feedback value IFB is large with respect to IREF, the PWM amplitude value AMP is controlled to be small.

The phase generator unit 12 generates a B-phase electrical angle having a phase difference of 90 degrees for the A-phase electrical angle output from the electrical angle generating unit 9 is output to the B-phase winding switching timing generator The As an example, a 90-degree phase difference corresponds to 4 steps at the time of 4 divided microsteps, so if TA is 8, TB becomes 4.

The A-phase switching timing generating unit 14-a, the A-phase electrical angle generated by the electrical angle generating unit 9, the control arithmetic unit 11 A-phase gate signal switching timing value generated based on the PWM amplitude value AMP in nA is generated and output to the + side input of the A phase comparator 15-a. In the B phase switching timing generation unit 14-b, the B phase electrical angle generated by the phase generation unit 12 and the control calculation unit 11 are output. A B-phase gate signal switching timing value nB is generated based on the PWM amplitude value AMP generated in step S5, and is output to the + side input of the B-phase comparator 15-b. Since the A-phase electrical angle and the B-phase electrical angle are generated with a phase difference of 90 degrees, the A-phase gate signal switching timing value nA and the B-phase gate signal switching timing value nB It is generated as a switching timing value that causes a current having a phase difference of 90 degrees to flow through the wire and the B-phase winding with the same amplitude.

The PWM counter 13 is a part in which the triangular wave generating circuit in the analog circuit is replaced with a digital system. The PWM counter 13 is an UP / DOWN counter that counts a clock signal having a constant period. The comparator 15-b and the sampling timing comparator 19 output to the negative side input. The PWM counter 13 counts up the counter value nCNT from 0 to the maximum value NMAX and then repeats the UP / DOWN count operation to count down to 0 again. However, the operation time for one UP / DOWN count operation is a triangular wave. This corresponds to time, that is, the PWM carrier period.

In the A-phase comparator 15-a, the gate signal switching timing value nA output from the A-phase switching timing generator 14-a is input to the + side input, and the PWM counter value nCNT output from the PWM counter 13 is set to the − side. Input to the input, the PWM source signal GA * is output to the A-phase complementary PWM generator 16-a, and the B-phase comparator 15-b outputs the gate signal switching timing value output from the B-phase switching timing generator 14-b. nB is input to the + side input, the PWM counter value nCNT output from the PWM counter 13 is input to the − side input, and the PWM source signal GB * is output to the B-phase complementary PWM generator 16-b.
If the gate signal switching timing values nA, nB are larger than the PWM counter value nCNT, GA * and GB * are H level, and if they are smaller, L level.

In the A-phase complementary PWM generation unit 16-a, the PWM source signal GA * output from the A-phase comparator 15-a is input, and the PWM signal GA into which a dead time for preventing simultaneous ON is inserted, and its complementary signal The GA bar is output to the switching element SA of the drive unit and the gate terminal of the SA bar, and the B phase complementary PWM generation unit 16-b receives the PWM source signal GB * output from the B phase comparator 15-b, The PWM signal GB into which the dead time for preventing simultaneous ON and the complementary signal GB bar are output to the gate terminals of the switching elements SB and SB bar of the drive unit.

FIG. 6 is a block diagram of a current feedback unit that performs a process of converting the motor current IS into a motor current feedback value IFB used for control calculation.
The motor current IS is converted into the motor current signal VIS by the current detection resistor RS5 and sent to the A / D converter 17, and the A / D sampling signal TSAMP generated by the A / D sampling timing generator 18 and the sampling timing comparator 19 is sent. Is sent to the A / D converter 21 at the timing determined by the above, where it is converted into a current feedback value IFB, which is digital data, and output to the control calculation unit 11.

The A / D sampling timing generation unit 18 receives the A phase electrical angle output from the electrical angle generation unit 9 and the values of the A phase gate signal switching timing value nA and the B phase gate signal switching timing value nB. Based on the information, the A / D sampling timing value nSAMP is determined and output to the + side input of the comparator.
The current IS flowing through the current detection resistor RS is the sum of the A-phase winding current and the B-phase winding current. Since PWM control is performed, each winding current flows from the power source + side to the power source-side. Then, the regeneration period flowing from the power source − side to the power source + side is repeated, and the shape of the IS waveform changes depending on the electrical angle.
In the present invention, the A / D converter detects the current during the period in which both the A-phase winding current and the B-phase winding current flow from the power source + side to the power source-side, avoiding the regeneration periods of the A phase and the B phase. Thus, the A / D conversion sampling timing nSAMP is determined according to the electrical angle. FIG. 7 is an explanatory diagram showing the relationship with the motor current signal VIS as an A-phase gate signal switching timing value nA, a B-phase gate signal switching timing value nB, and an A / D sampling timing value nSAMP.
When Figure 7-A is TA × [theta] s is less than 0 degrees 90 degrees or more (first quadrant), power from the power supply + side in CA winding and CB winding - a current flows to, nA> = NMAX / 2 and nB> NMAX / 2. If nSAMP at this time is set to NMAX / 2 or more, the motor current value during the period from the power supply + side to the power supply − side can be acquired.
Figure 7-B from the power supply + side in CA winding and CB bar windings when the TA × [theta] s is less than 180 degrees 90 degrees or more (second quadrant) power - because a current flows to, nA> NMAX / 2 NB <= NMAX / 2. At this time, if nSAMP is set to an intermediate value between nA and nB, that is, (nA + nB) / 2, the motor current value during the period from the power supply + side to the power supply − side can be obtained.
Figure 7-C is TA × [theta] s is less than 270 degrees 180 degrees power from the power supply + side in CA bar winding and CB bar windings when the (third quadrant) - a current flows to, nA <= NMAX / 2, nB <NMAX / 2. If nSAMP at this time is set to NMAX / 2 or less, the motor current value during the period from the power supply + side to the power supply − side can be acquired.
Figure 7-D is from the power supply + side in CA bar winding and CB winding when the TA × [theta] s is 270 degrees or more 360 degrees (0 degrees), less than (4th quadrant) power - a current flows to, nA <NMAX / 2, nB> = NMAX / 2. At this time, if nSAMP is set to an intermediate value between nA and nB, that is, (nA + nB) / 2, the motor current value during the period from the power supply + side to the power supply − side can be obtained.

In the sampling timing comparator 19, the A / D sampling timing value nSAMP output from the A / D sampling timing generator 18 is input to the + side input, and the PWM counter value nCNT output from the PWM counter is input to the − side input. Then, these values are compared, and a TSAMP signal as a comparison result is output to the sampler. The TSAMP signal becomes H level when the A / D sampling timing value nSAMP is larger than the PWM counter value, and becomes L level when the A / D sampling timing value nSAMP is smaller.

The sampler 20 receives the TSAMP signal output from the sampling timing comparator 19 and sends the motor current value VIS at the moment when the TSAMP signal rises from the L level to the H level to the A / D converter 21. The A / D converter 21 converts the value into digital data, and outputs the converted value to the control calculation unit 11 as a current feedback value IFB.

FIG. 2 is a block diagram of a drive circuit of a bipolar connection type two-phase stepping motor according to a second embodiment of the present invention. The drive circuit is roughly composed of a control unit 1 and a drive unit 2-2. The configuration is the same as that of the unipolar connection type two-phase stepping motor of the first embodiment.
The drive unit 2-2 includes a winding 6 of a two-phase stepping motor with bipolar connection, semiconductor switching element groups 7-1 and 7-2, and a current detection resistor 5. A bipolar-connected two-phase stepping motor includes an A-phase winding CA and a B-phase winding CB. One end of the A-phase winding CA is connected to the drain terminals of the switching elements SA1, SA3, the other end is connected to the drain terminals of the switching elements SA2, SA4, and one end of the B-phase winding CB is connected to the switching elements SB1, SB3. The other end is connected to the drain terminals of the switching elements SB2 and SB4. The source terminals of the upper switching elements SA1, SA2, SB1, and SB2 are connected to the power source + side, and the source terminals of the lower switching elements SA3, SA4, SB3, and SB4 are connected to one end of the current detection resistor 5, Connected to the A / D converter 17 of the controller 1. The other end of the current detection resistor 5 is connected to the power supply side.
The switching elements SA1 and SA4 are turned on / off by a gate signal GA output from the control unit, and the switching elements SA2 and SA3 are turned on / off by a gate signal GA bar output from the control unit, and the switching elements SB1 and SB4. Are turned on / off by a gate signal GB output from the control unit, and the switching elements SB2 and SB3 are turned on / off by a gate signal GB bar output from the control unit. The switching elements SA1, SA2, SB1, and SB2 connected to the power source + side are connected to the control unit 1 via predrivers 8-a, 8-b, 8-c, and 8-d for converting the level of the gate signal. Connected.

FIG. 8 is a diagram illustrating a case where switching by the triangular wave comparison complementary PWM method is performed for the A phase of the winding of the two-phase stepping motor of bipolar connection. The following description is given for the A phase, but the same applies to the B phase. SA1 and SA4 and SA2 and SA3 are in a complementary relationship. When SA1 and SA4 are ON, SA2 and SA3 are OFF, and when SA1 and SA4 are ON, SA2 and SA3 are OFF. Here, the triangular wave is standardized with a maximum value of 0 and a minimum value of 1. The triangular wave is always compared with the PWM switching timing value n. When the magnitude of the triangular wave is larger than n, SA1 and SA4 are ON, SA2 and SA3 are OFF, and when smaller than n, SA1 and SA4 are OFF and SA2. , SA3 is turned ON.
FIG. 8A shows ON / OFF of SA1, SA4 and SA2, and SA3 when n is 0.5, and current IA flowing through the CA winding. When n is 0.5, since the length of the SA ON period and the SA bar ON period are equal, almost no current flows due to the influence of the winding inductance.
FIG. 8B shows ON / OFF of SA1, SA4 and SA2, and SA3 when n is smaller than 0.5, and current IA flowing through the CA winding. Since the ON period of SA1 and SA4 is longer than the ON period of SA2 and SA3, the current flows from the power source + side to the power source-side through the SA1, CA winding and SA4 during the SA1 and SA2 ON periods. In the ON period, the current is regenerated from the power source minus side through the SA3, CA winding, and SA2 to the power source plus side. That is, the current flows from the power source + to the power source − on the mountain side of the triangular wave, and the current is regenerated from the power source − to the power source + on the valley side.
FIG. 8C shows ON / OFF of SA1, SA4, SA2, and SA3 when n is larger than 0.5, and IA of the current flowing through the CA winding. Since the ON period of SA2 and SA3 is longer than the ON period of SA1 and SA4, the current flows from the power source + side to the power source negative side through the SA2, CA winding, and SA3 during the SA2 and SA3 ON periods. In the ON period, the current is regenerated from the power source − side to the power source + side through SA4, CA winding, and SA1. That is, the current flows from the power source + to the power source − on the valley side of the triangular wave, and the current is regenerated from the power source − to the power source + on the mountain side.

Comparing FIG. 4 and FIG. 8, the current IA is the same for the unipolar connection and the bipolar connection, and the configuration of the control unit 1 may be the same whether the motor is a unipolar connection or a bipolar connection.

The drive circuit for a two-phase stepping motor according to the present invention is suitable for driving a two-phase stepping motor having a unipolar connection or a bipolar connection, and requires a small number of parts. In addition, since all the functional blocks of the control unit can be configured with a microcomputer and control is simple, it can also be configured with a microcomputer with low processing capability, contributing to the miniaturization and cost reduction of the drive circuit. Then, the range in which the stepping motor can be used as various drive sources is expanded.

It is a block diagram which shows the structure of the drive circuit of the two-phase stepping motor of the unipolar connection which becomes this invention. It is a block diagram which shows the structure of the drive circuit of the two-phase stepping motor of the bipolar connection which becomes this invention. It is a block diagram which shows the structure of the control part of the drive circuit of the two-phase stepping motor which becomes this invention. It is a figure explaining the current waveform for one phase of the two-phase stepping motor of the unipolar connection in a triangular wave comparison complementary PWM system. It is a figure explaining a motor current waveform changing with the presence or absence about the electric current target value correction | amendment in this invention. It is explanatory drawing of the current feedback part of the two-phase stepping motor drive circuit which becomes this invention. The figure explaining always detecting a positive motor current value by changing A / D conversion sampling timing with the motor electrical angle in the present invention. It is a figure explaining the current waveform for 1 phase of the 2-phase stepping motor of the bipolar connection in a triangular wave comparison complementary PWM system. It is a block diagram which shows the structure of the drive circuit of the two-phase stepping motor of the unipolar connection by the conventional system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control part of 2-phase stepping motor according to the present invention 1-1 Control part of 2-phase stepping motor according to conventional method 2-1 Driving part of unipolar 2-phase stepping motor according to the present invention 2-2 Bipolar connection according to the present invention 2-phase stepping motor drive unit 2-3 2-phase stepping motor drive unit 2-4 2-phase stepping motor drive unit with unipolar connection according to the conventional method 3 Unipolar connection 2-phase stepping motor winding 4 Unipolar connection 2 Phase stepping motor switching element group 5 Current detection resistor RS
5-a A phase current detection resistor RSA
5-b B phase current detection resistor RSB
6 Bipolar connection 2-phase stepping motor winding 7-1 Bipolar connection 2-phase stepping motor upper switching element group 7-2 Bipolar connection 2-phase stepping motor lower switching element group 8-a, 8-b, 8-c, 8-d Pre-driver 9 Electrical angle generator 10 Current target value generator 10-a A phase current target value generator 10-b B phase current target value generator 11 Control operation unit 11-a A phase control Calculation unit 11-b B phase control calculation unit 12 Phase generation unit 13 PMW counter 13-1 PWM carrier signal generation unit 14-a A phase switching timing generation unit 14-b B phase switching timing generation unit 15-a A phase comparator 15 -B B-phase comparator 16-a A-phase complementary PWM signal generator 16-b B-phase complementary PWM signal generator 17 A / D converter 18 A / D sampling timing generator 19 Sampling timing comparator 20 Sampler 21 A / D converter 22 Motor winding and switching element of 2-phase stepping motor 23-a A phase current control unit 23-b B phase current control unit 24-a A phase Filter 24-b B phase filter

Claims (4)

A circuit for driving a unipolar-connected two-phase stepping motor. A control unit that receives an input signal from the outside and generates a control signal; and a semiconductor switching element group that receives the signal from the control unit and switches the winding current of the motor. and a driving unit provided with one current sensing element connected to a current supply common terminal, there is controlled by the triangular wave comparison complementary PWM mode, the control unit, an electrical angle signal subjected to the outside from the input signal An electrical angle generation unit, a current target value generation unit, a control calculation unit, a phase generation unit, a PWM counter, an A phase switching timing generation unit, a B phase switching timing generation unit, an A phase comparator, and the B-phase comparator, the a-phase complementary PWM signal generating unit, and the B-phase complementary PWM signal generating unit, the more configured to an a / D conversion unit, the control unit inside the a / D converter Wherein the A / D sampling timing generator, and the sampling timing comparator, a sampler, a more structure as A / D converter, the motor current signal detected as a combined value of the current flowing in all windings by the current detecting element When the digital signal is converted by the A / D converter, the timing of inputting the motor current signal to the A / D converter is switched according to the electrical angle signal, and the current is supplied to the winding + A drive circuit for a two-phase stepping motor with a unipolar connection, characterized in that only a motor current value during a period of flowing from the power source to the power source side can be acquired. 2. The unipolar connection according to claim 1, wherein the output of the current target value generation unit corresponds to an electrical angle range and is output after being corrected by the following mathematical formula 1. Drive circuit for a 2-phase stepping motor.
However, the compensation value,
“Equation 1” IREF = IREFMAX × sin (TA × θs−45 × (2d−3))
Here, IREF is current target value, IREFMAX is the maximum value of the current target value, the number of steps for setting the electrical angle TA, when a unit step angle [theta] s, d is the electrical angle (TA × represents the quadrant number of [theta] s), the electrical angle (TA × [theta] s) is 0 degrees or more is less than 90 degrees d = is less than 1,90 ° than 180 ° d = 2,180 degrees 270 degrees than at any For example, if d = 3 and 270 degrees or more and less than 360 degrees, d = 4 . A circuit for driving a bipolar-connected two-phase stepping motor, which receives an input signal from the outside and generates a control signal, receives a signal from the control unit, four sets of pre-driver circuits, and eight motors A semiconductor switching element group that performs winding current switching, and a drive unit provided with one current detection element connected to a current-carrying common terminal of two sets of bipolar-connected windings. It is one that controls the control unit and the electrical angle generator for generating an electrical angle signal from the input signal received from the outside, and a current target value generating unit, and a control arithmetic unit, a phase generating unit, and the PWM counter A phase switching timing generation unit, B phase switching timing generation unit, A phase comparator, B phase comparator, A phase complementary PWM signal generation unit, B phase complementary PW The signal generation unit and the A / D conversion unit are configured. The A / D conversion unit in the control unit is configured by an A / D sampling timing generation unit, a sampling timing comparator, a sampler, and an A / D converter. , when converting a motor current signal detected as a combined value of the current flowing in all windings by the current detecting resistor into a digital signal by the a / D converter, inputs the motor current signal to the a / D converter The timing to perform is switched according to the electrical angle signal, and only the motor current value during the period when the current always flows from the power source + side to the power source-side can be obtained for the winding. A drive circuit for a two-phase stepping motor with bipolar connection. 4. The bipolar connection according to claim 3 , wherein the output of the target current value generator corresponds to an electrical angle range and is output after being corrected by the following mathematical formula 2. 5. Drive circuit for a 2-phase stepping motor.
However, the compensation value,
“Equation 2” IREF = IREFMAX × sin (TA × θs−45 × (2d−3))
Here, IREF is current target value, IREFMAX is the maximum value of the current target value,
Number of steps for setting the electrical angle TA, when a unit step angle [theta] s, d represents the quadrant number of the electrical angle (TA × θs), the electrical angle (TA × [theta] s) is 0 degrees 90 degrees If it is less than d, d = 1, if it is 90 degrees or more and less than 180 degrees, d = 2, if it is 180 degrees or more and less than 270 degrees, d = 3, if it is 270 degrees or more and less than 360 degrees, d = 4 .

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