RU2737662C1 - Method of stabilizing current level in winding of two-winding step motor operating in full-step mode, and driver for its implementation - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the electrical equipment. Method of current level stabilization in winding of double-winding SM, operating in full-step mode, at which winding power supply is carried out by means of two power half-bridges. At increase of current in lower arm of that power half-bridge, in which lower switch is closed, above specified first upper threshold value at open upper switches of both power half-bridges current level is compared in lower arm of that power half-bridge, in which lower switch is closed, with specified second upper threshold value, when exceeding of which this lower key is opened. Thereafter, current level is controlled in the lower arm of the power half-bridge where the current flows in the negative direction. And, when current level reaches a predetermined second lower threshold value, closing the lower switch of the power half-bridge, which provides current flow in the winding in the previous direction. At that, the specified second upper threshold value is selected above the specified first upper threshold value. A given second lower threshold is selected above a given first lower threshold. In order to implement method of current level stabilization in double-winding SM winding, its driver includes two adders, three program-controlled keys, a third comparator, a second, a third and a fourth reference voltage source and a NOT logic element in the current stabilization signal generation unit.

EFFECT: technical result consists in improvement of accuracy of stabilization of current level at any moment of its flow in winding of step motor (SM) in any possible case of switching of power bridges.

2 cl, 6 dwg

Description

The proposed invention relates to electrical engineering, namely, to methods and devices for controlling stepper motors (SM).

Most often, during the operation of a two-winding stepper motor, a full-step mode is used, as it allows developing the maximum torque. In this case, the regulation of the current in the windings is provided by a pulse regulator, which, during the interval of disconnecting the winding from the current source, provides a slow decay mode to minimize the switching frequency and ripple level.

Known technical solutions that are used to stabilize the current level in the winding of a two-winding stepper motor when operating in full-step mode. The most widely used methods of stabilizing the current in the stepper motor winding include cyclic supply of the supply voltage to the winding, comparing the current in the supply diagonal of the bridge with a threshold value in the time interval from the moment the voltage is applied until the current reaches the threshold value, and removing the supply voltage from the winding to a fixed value. by duration time interval. This solution is used in most modern stepper motor drivers. For example, in A4989 Allegro MicroSystems [1] or TMC262 TRJNAMIC Motion Control GmbH & Co. KG [2]. The need to use a fixed off-time interval is caused by the lack of information about the current value when the stepper motor winding is disconnected from the power supply. The disadvantage of this method is due to the fact that, despite the continuity of the current in the stepper motor winding, when a resistor connected between the lower point of the supply diagonal of the power bridge and the minus of the power supply is used as a sensitive element of the current sensor, the current in it is interrupted when the winding supply voltage is turned off. Because of this, regardless of the current, at the end of the "Fixed Off-Time", voltage must be applied to the winding. This, if the current at this moment is greater than the threshold value, leads to an additional increase in the current instead of decreasing it and an increase in the switching frequency, which, in turn, increases the heating of the elements of the power bridge. The description of the operation of the keys of the power bridge and the nature of the change in currents are given, for example, in [3].

Also known is the technical solution described in [4], in which two measuring resistors are used in the lower arms of each supply half-bridge, which allows to continuously monitor the current flowing through the SM winding. This solution makes it possible to increase the accuracy of stabilization of the current in the stepper motor winding and to avoid voltage supply to the winding when the current in it exceeds a predetermined threshold value. This allows you to reduce power consumption and improve the reliability of the keys. But this decision, taken as a prototype, does not stabilize the current in the stepper motor winding when the power supply is disconnected, if the self-induction emf arising from the stepper motor armature oscillations causes a current in the winding that exceeds its stabilized value.

The objective of the proposed invention is to expand the functionality, allowing to provide the required accuracy of stabilization of the current in the winding at a given stationary level for any investigated modes of operation of the SM.

The solution to this problem is achieved due to the fact that with an increase in the current in the lower arm of the power half-bridge in which the lower switch is closed, above the specified first upper threshold value with the upper keys of both power half-bridges open, the current level in the lower arm of the power half-bridge in which the lower key is closed, with a given second upper threshold value, upon exceeding which this lower key is opened. After that, the current level is monitored in the lower arm of that power half-bridge in which the current flows in the negative direction. And, when the current level reaches a predetermined second lower threshold value, the lower key of that power half-bridge is closed, which ensures the current flow in the winding in the same direction. In this case, the predetermined second upper threshold value is selected above the predetermined first upper threshold value, and the predetermined second lower threshold value is selected above the predetermined first lower threshold value. Under the current level we mean its absolute value, regardless of the direction of its flow in the winding.

To implement the proposed method for stabilizing the current level in the winding of a two-winding stepper motor operating in a full-step mode, two adders, three software-controlled keys, a third comparator, second, third and fourth reference voltage sources and a logic element NOT in the signal conditioning unit are introduced into its driver stabilization of the current. In this case, the additional output of the current stabilization signal generation unit, which is the output of the logic element 2OR, is connected to the additional input of the control signal generation unit. The output of the 2OR logic element is connected to the input of the NOT logic element, the output of which is connected to the second input of the 2I logic element. The first input of logic element 2OR is connected to the second input of the current stabilization signal generating unit, and its second input is connected to the third input of the current stabilization signal generating unit, to which the output of the third comparator is connected. The inverting input of the first comparator is connected to the output of the first software-controlled key. The non-inverting input of the second comparator is connected to the output of the second software-controlled key, and its inverting input is connected to the output of the second reference voltage source. The non-inverting input of the third comparator is connected to the output of the third reference voltage source, and its inverting input is connected to the output of the third software-controlled key. The first and second inputs of the programmable keys are connected respectively to the outputs of the first and second adders, the first inputs of which are connected to the output of the fourth reference voltage source. Moreover, the second input of the first adder is connected to the upper terminal of the first measuring resistor, and the second input of the second adder is connected to the upper terminal of the second measuring resistor.

The essence of the proposed technical solution is illustrated by drawings.

FIG. 1. Functional diagram of a two-winding stepper motor driver with a winding current level stabilization loop that implements the proposed method.

FIG. 2. Scheme of current flow in the elements of the power bridge and through the stepper motor winding in different modes of switching the power circuit.

FIG. 3. Oscillogram of the process of changing the current in the stepper motor winding during its stabilization using the proposed technical solution, obtained by the method of computer simulation.

FIG. 4. Oscillograms obtained by the method of computer simulation of transient processes of voltage change on the winding and currents in the SM winding and the lower arms of the power half-bridges when using the proposed technical solution.

FIG. 5. Oscillograms of transient processes of changes in currents in the stepper motor windings obtained by the method of computer simulation when working out the same section of a typical cyclogram using the prototype technical solution (figure a) and the proposed technical solution (figure b).

FIG. 6. Block diagram of the configuration of the internal modules of the microcontroller when using it to implement the proposed technical solution.

Shown in FIG. 2, the diagram allows you to explain how the current flow circuit is formed in the stepper motor winding when switching the keys of the power bridge in different sections of the current stabilization loop.

Let's take the direction of the current in the winding from left to right as a positive one. Then when the supply voltage is applied to the power bridge and the closed state of the upper key B of the left power half-bridge and the lower key C of the right power half-bridge, the current through the SM winding will flow in a positive direction (see Fig. 2, a). Its path will pass from the positive terminal of the power supply Vm through the open transistor VT1, the stepper motor winding (Lm), the open transistor VT4 and the measuring resistor R2 to the negative terminal of the power supply 0V.

FIG. 3 shows the oscillogram of the process of changing the current in the stepper motor winding near the stabilized level of 5 V, obtained by the method of computer simulation, when it is stabilized using the proposed technical solution. When the current exceeds the predetermined first upper threshold value Itu1 (point A in FIG. 3), the upper switch B of the left power half-bridge is opened, and the current flow pattern in the winding acquires the state shown in FIG. 2, b. In this case, the current in the winding retains its direction and closes in the circuit: the stepper motor winding (Lm), open transistor VT4, measuring resistor R2, measuring resistor R1 and diode VD2. With such a state of the circuit and the absence of significant values of the self-induction emf that occurs in the winding when the SM armature rotates, the current in the winding begins to drop. If its level, measured in the lower arm of the right power half-bridge, falls below the predetermined first lower threshold value Itd1, which corresponds to point B on the oscillogram in FIG. 3, the upper switch B of the left power half-bridge is closed, and the winding current flow pattern returns to the state shown in FIG. 2, a, and the supply voltage is applied to the winding again.

Further, the current level in the winding will increase, and the cycle of operation of the current stabilization algorithm will be repeated until the situation shown in the simulation section of the process of changing the current after point C arises. Here, after opening the upper key B of the left power half-bridge and transition of the power circuit to the state shown in FIG. 2b, the current level in the winding does not fall to the predetermined first lower threshold value Itd1, but increases due to the fact that when the armature rotates at a sufficient speed, a self-induction emf of a significant value arises, which causes a current in the winding of the same positive direction. Then, when the current level exceeds the predetermined second upper threshold value Itu2 (point D in Fig. 3), the lower switch C of the right power half-bridge is opened, after which the power circuit goes into the state shown in Fig. 2, p. In this case, the current in the winding again retains its direction and, since the voltage applied to the stepper motor winding turns out to be higher than the supply voltage, it flows through the circuit: the negative terminal of the power supply, measuring resistor R1, diode VD2 and diode VD3 to the positive terminal of the power supply. In this case, a part of the energy stored in the stepper motor winding is transferred to the power source, and the current level begins to fall. The control of the current level in the winding in this state of the power circuit is carried out in the lower arm of that power half-bridge in which the current flows in the negative direction, i.e. in the lower shoulder of the left half-bridge (see Fig. 2, c).

When the current level reaches the predetermined second lower threshold value Itd2 (point E in Fig. 3), the lower switch of that power half-bridge is closed, which ensures the current flow in the winding in the same direction, i.e. the lower switch C of the right power half-bridge, after which the power circuit returns to the state shown in FIG. 2, b. After that, two options for further changing the current are possible. If the voltage applied to the SM winding, due to the action of the self-induction emf, will still be higher than the supply voltage, then the current level in the winding, which is now measured again in the lower arm of the right power half-bridge, will increase. And the cycle of regulation of the current level between the values of Itd2 and Itu2 will be repeated again (see Fig. 3). If the voltage applied to the SM winding, after the transition of the power circuit to the state shown in FIG. 2b, becomes less than the supply voltage, then the current level in the winding will decrease. Such a state arose in computer simulation after the current reached the value Itd2 at point F (see the oscillogram of the current change in Fig. 3). Then the current level in the winding begins to decrease and reaches the predetermined first lower threshold value Itd1 (point G in the graph of Fig. 3). After that, the upper switch B of the left power half-bridge is closed, the power supply circuit changes to the state shown in FIG. 2, a, and the process of stabilizing the current level in the stepper motor winding is resumed by the proposed method.

When the current in the SM winding flows in the opposite direction, the process of its stabilization is carried out in the same way. How the switching will be carried out in the power supply circuit of the stepper motor winding in this case is shown in Fig. 2 d, e, f.

The processes of changing the voltage on the stepper motor winding and currents in the winding and the lower arms of the power half-bridges when using the proposed technical solution, obtained by computer simulation, are shown in Fig. 4 for winding A SM for a short period of time. In these oscillograms, the current in the winding (IA) is shown as a thin solid line, the voltage on the winding (UA) is shown by a dash-dot line, the current in the lower arm of the left power half-bridge (IA1) is shown by a dashed line, and the current in the lower arm of the right power half-bridge (IA2) is dashed line.

The time interval indicated in FIG. 4 [t0, t1] corresponds to the state of the power circuit shown in FIG. 2, a. During this time interval, the current in the IA winding flows in a positive direction, the UA voltage applied to the winding has a positive value. The current in the lower arm of the left power half-bridge IA1 is zero, and the current in the lower arm of the right power half-bridge IA2 is positive and equal to the current in the winding IA. The time interval indicated in FIG. 4 [t1, t2] corresponds to the state of the power circuit shown in FIG. 2, b. During this time interval, the current in the IA winding flows in the positive direction, the UA voltage applied to the winding is zero. The current in the lower arm of the left power half-bridge IA1 has a negative value, and its level is equal to the current level in the winding IA. The current in the lower arm of the right power half-bridge IA2 is positive and equal to the current in the winding IA. The time interval indicated in FIG. 4 [t3, t4] corresponds to the state of the power circuit shown in FIG. 2, p. During this time interval, the current in the winding IA still flows in the positive direction, and the voltage UA applied to the winding has a negative value. The current in the lower arm of the left power half-bridge IA1 has a negative value, and its level is equal to the current level in the winding IA. The current in the lower arm of the right power half-bridge IA2 is zero. The oscillograms shown in Fig. 4, make it possible to understand how the operations of closing and opening the corresponding keys, performed when the current in the stepper motor winding changes, makes it possible to ensure its stabilization under different operating conditions of the stepper motor.

FIG. 5 shows the processes of changing the current in the stepper motor windings obtained by the method of computer simulation during the development of a section of a typical cyclogram of changing the stepper motor shaft position. FIG. 5, a shows the processes obtained using the technical solution-prototype, and FIG. 5, b - the proposed technical solution. In these graphs, the process of changing the current IA in the winding A is shown by a thick solid line, the process of changing the current IB in the winding B by a dashed line, and the process CG of changing the set value of the SM shaft position (cyclogram) is shown by a thin solid line. Comparison of the graphs shown in FIG. 5 a and b, allows us to conclude that the proposed technical solution provides stabilization of the current in the stepper motor windings with a given accuracy in all considered modes of stepper motor operation. Whereas the use of the prototype technical solution does not provide current stabilization in the work areas, where the action of the self-induction emf when the supply voltage is disconnected increases the current level in the winding to a value exceeding the specified first upper threshold value.

The predetermined second upper threshold value is selected above the predetermined first upper threshold value, and the predetermined second lower threshold value is selected above the predetermined first lower threshold value to provide a sequential transition when the current flow pattern changes from the state shown in FIG. 2a, into the state shown in FIG. 2b, and further into the state shown in FIG. 2, c, and vice versa. This will ensure that there are no contradictions when closing and opening keys and the necessary sequence of these operations.

The functional diagram of the stepper motor driver implementing the proposed method for stabilizing the current level in the stepper motor winding operating in full-step mode is shown in Fig. 1. The circuit for stabilizing the current level in the stepper motor winding, implemented in the driver, contains a series-connected first reference voltage source (ION) 1, a first comparator 2, a current stabilization signal generation unit 3 and a control signal generation unit 4. And also the second comparator 5, the first and the second measuring resistors 6 and 7, the drivers of the left and right half-bridges 8 and 9 and two power half-bridges 10 and 11. Moreover, the first and second outputs of the control signal generation unit are connected to the corresponding inputs of the left half-bridge driver. The third and fourth outputs of the control signal generation unit are connected to the corresponding inputs of the right half-bridge driver. Simultaneously, the first and second outputs of each driver are connected to the control inputs of the corresponding power half-bridges, the upper points of which are connected to the positive terminal of the stepper motor power supply, and the midpoints to the stepper motor winding. In this case, the lower point of the left power half-bridge is connected through the first measuring resistor and the lower point of the right power half-bridge through the second measuring resistor to the negative terminal of the stepper motor power supply. The third and fourth inputs of both drivers are connected, respectively, to the positive and negative terminals of the driver power supply, and their third outputs, respectively, to the middle points of the left and right power half-bridges. The block for generating the current stabilization signal contains a logic element 2I 12 and a logic element 2 OR 13, whose output is the output of the block for generating a current stabilization signal. The first input of the logic element 2I is the first input of the current stabilization signal generating unit and is connected to the output of the first comparator. The second input of the current stabilization signal generating unit is connected to the output of the second comparator and the negative terminals of all power supplies are connected to each other. The current level stabilization circuit also contains two adders 14 and 15, three programmable switches 16, 17 and 18, a third comparator 19, second, third and fourth reference voltage sources 20, 21 and 22. A logic element is introduced into the current stabilization signal generation unit 3 NOT 23. The additional output of the block for generating the current stabilization signal, which is the output of the logic element 2 OR 13, is connected to the additional input of the unit for generating control signals 4. The output of the logic element 2 OR 13 is connected to the input of the logic element NOT 22, the output of which is connected to the second input of the logic element 2I 12. The first input of logic element 2 OR 13 is connected to the second input of the current stabilization signal generating unit 3, and its second input is connected to the third input of the current stabilization signal generating unit 3, to which the output of the third comparator 19 is connected. The inverting input of the first comparator 2 is connected to the output of the first software-controlled key 16. Non-inverting the input of the second comparator 5 is connected to the output of the second software-controlled key 17, and its inverting input is connected to the output of the second reference 20. The non-inverting input of the third comparator 19 is connected to the output of the third reference 21, and its inverting input is connected to the output of the third software-controlled key 18. The first and second inputs of the programmable keys 16, 17 and 18 are connected respectively to the outputs of the first and second adders 14 and 15, the first inputs of which are connected to the output of the fourth ION 22. Moreover, the second input of the first adder 14 is connected to the upper terminal of the first measuring resistor 6, and the second input of the second adder 15 is connected to the upper terminal of the second measuring resistor 7.

Since the driver of a two-winding stepper motor contains two identical circuits for stabilizing the current level in the windings of phases A and B of the stepper motor, its operation will be considered on the example of one phase A.

The control of the direction of the current in the winding, as already noted, is carried out by choosing one of two pairs of diagonally located keys VT1, VT4 or VT2, VT3 (see Fig. 2, a and d). Moreover, to ensure the continuity of the current in the measuring resistors R1 and R2, the current is stabilized by modulating the open state of one of the upper keys VT1 or VT3. The path of current flow in the circuit in this case is shown in FIG. 2a and b or in FIG. 2d and f.

To exclude the growth of current in the stepper motor winding when only one lower key is closed, the transition to the return of energy to the power source is used, which is achieved by opening all the keys. In this case, the control of the current level must be carried out not in the measuring resistor R2 (see Fig. 2, c), in which the current flows in the positive direction when the lower switch is closed, but in the resistor R1, in which the current flows in the negative direction. To solve this problem, the signals from the measuring resistors R1 and R2 are added with a constant reference voltage Vref4 in adders 14 and 15 (see the functional diagram in Fig. 5). A resistive voltage divider can be used as a reference voltage source. The parameters of the adders and voltage divider are selected so as to provide an output voltage equal to half the supply voltage of the circuit at zero current in the controlled measuring resistor and the voltage swing required for the regulator to operate at the maximum current through it.

A possible adder circuit (14 or 15) and the calculation of its parameters are described in the book [5] on p. 77 and in article [6]. A similar adder can be built using the MCP6V02-E / SN / operational amplifier [7]. The remaining functional units of the regulator shown in the left part of FIG. 6, can be performed on the modules of the periphery independent of the core (Core Independent Peripheral, CIP) of the PIC16F1778-I / SO microcontroller [8]. The functioning of such peripherals is almost independent of the clock frequency of the microcontroller and its state (RUN, IDLE, SLEEP), and is configured by the microcontroller program, after which it functions independently.

The drivers of the left and right half-bridges and the power half-bridges themselves can be made, for example, in accordance with their diagrams and descriptions given in the patent description [4].

From the outputs of the adders 14 and 15, the signals are fed to the block of programmable keys 16, 17 and 18 (see Fig. 5), which are switched simultaneously when the direction of the current in the controlled SM winding changes. In the functional diagram, they are shown in the position FWD, corresponding to the flow of current in the forward direction through R1 (the first measuring resistor 6). The keys can be executed on multiplexers included in the comparators CMP1-CMP3 (see Fig. 6), and are controlled by setting the corresponding values in their control registers. In addition, hysteresis is activated in the comparators by means of these registers, ensuring the presence of a dead band between the upper and lower threshold values of each comparator. Thus, the value of the upper threshold value of the comparator will be Vref + Vhys, and the lower one - Vref -Vhys, where Vref is the value of the reference voltage, and Vhys is the size of the deadband of this comparator. So on the comparator CMP1, the first upper and first lower threshold values are formed. On the comparators CMP2 and CMP3, the second upper and second lower threshold values are formed in the same way, but only on one (CMP2) - to stabilize the current level with a negative direction, and on the other (CMP3) - to stabilize the current level with a positive direction.

The circuit that stabilizes the current level by modulating the open state of the upper key with the closed lower key and described in the prototype [4] is implemented using the first comparator 2 (see Fig. 1). Depending on the direction of the current in the winding, the inverting input of the specified comparator will be connected to the output of the corresponding adder of the first 14 or the second 15. The threshold voltage Vref1 is formed by the first reference 1. The output signal of the second comparator 5, through the logic element 2I 12 of the current stabilization signal generation unit 3, controls the operation of the control signal formation unit 4. The above logic element 2I 12 blocks the passage of the signal of the first comparator 2 when any of the comparators is triggered - the second comparator 5 or the third comparator 19, which control the excess of the stepper motor winding current of the specified second upper threshold value Itu2. The signals from the outputs of these comparators (5 and 19) are combined by a logical element 2 OR 13, as a result of which the output signal of the current stabilization signal generating unit 3 is formed, from the additional output of which it is fed to the additional input of the control signal generation unit 4. As a result, this signal provides disconnection of all keys of the power half-bridges that control this stepper motor winding.

An example of the implementation of the functions described above using the resources of the PIC16F1778 [8] microcontroller is shown in Fig. 6. The pin numbers of the microcontroller shown in FIG. 6 correspond to the SOIC 28 package [8]. Accordingly, conclusions 13, 14, 12 and 11 are the first, second, third and fourth outputs of the control signal generating unit (see Fig. 6). Pins 2 and 3 are connected respectively to the first and second inputs of each of the programmable switches 16, 17 and 18. Lead 17 is connected to the positive terminal of the 5-volt power supply. Finally, pins 5 and 16 are connected to the negative side of the 5V power supply.

The signals from the outputs of the first and second adders 14 and 15 (see Fig. 1) are fed to pins 2 and 3 of the microcontroller (see Fig. 6), to which the inputs of the comparators CMP1-CMP3 are connected. The state of the keys of the multiplexers of these comparators, shown in the diagram of FIG. 6, corresponds to the flow of current through the measuring resistor R1 with the closed state of the lower key in the left power half-bridge and the upper one in the right. The signal from the output of the comparator CMP1 (see Fig. 6) is fed to the input of the logic element 2I executed on the configurable logic cell CLC1 (CONFIGURABLE LOGIC CELL) of the microcontroller, configured to perform the AND-OR function. The signal from the CLC1 output is fed to the corresponding inputs of the control signal generating unit only in the absence of a high logic level signal from the output of logic element 2 OR, executed on the CLC2 cell configured to perform the AND-OR function.

The block for generating control signals can be built in a microprocessor (see Fig. 6) on the module of the generator of the complementary output COG1 (COMPLEMENTARY OUTPUT GENERATOR MODULES). The output signals of the control signal generation unit having logic levels of 5 volts are converted by the drivers of the left and right half-bridges into signals having the levels necessary for the operation of the field-effect transistors of the corresponding power half-bridge. The COG1 module is configured to operate in Forward and Reverse FULL-BRIDGE MODES, in which two out of four outputs are always active, and the other two are passive. In this case, one of the active outputs, which controls the upper key of the corresponding power half-bridge, is modulated by a pulse signal according to the signal from the output of the CMP1 comparator, arriving at the inputs that are the sources of the rising and falling edges - Rising event source (RES) and Falling event sources (FES), respectively. To disable all keys, the ASE2 (Auto-Shutdown Even) input is used, connected to the output of the logic cell CLC2.

We especially note that the choice of the numerical parameters of the upper and lower threshold values of the current during its stabilization, firstly, is determined by the required accuracy of current stabilization, and, secondly, the achieved stabilization accuracy is limited by the permissible speed of the keys and other electronic circuit elements used in the implementation of the device ... Referring to FIGS. 3-5 results of computer simulation of the proposed technical solution ensured the accuracy of current stabilization within 1.5%, the switching frequency of the keys does not exceed 25 kHz, which is quite acceptable for the electronic circuit elements used in the implementation of the proposed driver.

The presented results of computer modeling confirm the operability and effectiveness of the proposed technical solution, and also prove that the task of the invention has been solved.

INFORMATION SOURCES

1. A4989-Datasheet.pdf, Inc. www.allegromicro.com.

2. TMC262 DATASHEET (Rev. 2.14 / 2016-JUL-14). www.trinamic.com.

3. Borisevich A.V., Glebko D.V. An approach to the optimal switching strategy for the current regulator in the windings of a stepper motor // Modern Technics and Technologies. 2015. No. 3 [Electronic resource]. URL: http://technology.snauka.ru/2015/03/5935.

4. Patent RU 2708073, 04.12.2019, bul. No. 34. A method for stabilizing the current level in the winding of a two-phase bipolar stepper motor in full-step mode and a driver for its implementation.

5. Aleksenko A.G., Kolombet E.A., Starodub G.I. Application of precision analog ICs. - M .: Radio and communication, 1981 .-- 224 p.

6. Averager and summer circuits, http://www.allaboutcircuits.com/vol_3/chpt_8/8.html.

7.22058c.pdf www.microchip.com/product/en/MCP6V02.

8. DS40001819B.pdf www.microchip.com/product/en/PIC16F1778.

Claims (2)

1. A method of stabilizing the current level in the winding of a two-winding stepper motor operating in full-step mode, in which the winding is powered by two power half-bridges, and the desired direction of the current in the winding is achieved by simultaneously closing the upper key of one half-bridge and the lower key of the other, and to stabilize the level current in the winding when the current in the lower arm of the power half-bridge in which the lower key is closed, a certain specified first upper threshold value is opened, the upper key of another power half-bridge is opened, turning off the supply voltage for a period of time until the current level drops to the specified first lower threshold value , after which the next switching on of the supply voltage is performed, again closing the upper key of another power half-bridge, characterized in that when the current in the lower arm of the power half-bridge in which the lower key is closed, it is higher than the specified first upper threshold value with open the upper keys of both power half-bridges compare the current level in the lower arm of that power half-bridge in which the lower switch is closed, with the specified second upper threshold value, when exceeding which this lower switch is opened, after which the current level is monitored in the lower arm of that power half-bridge, in where the current flows in the negative direction, and when the current level reaches a predetermined second lower threshold value, the lower switch of that power half-bridge is closed, which ensures the current flow in the winding in the same direction, while the predetermined second upper threshold value is selected above the predetermined first upper threshold value and the predetermined second lower threshold value is selected above the predetermined first lower threshold value. 2. Driver of a two-winding stepper motor, the circuit for stabilizing the current level in the winding of which contains a series-connected first reference voltage source, a first comparator, a current stabilization signal generation unit and a control signal generation unit, as well as a second comparator, first and second measuring resistors, left and right half-bridges and two power half-bridges, where the first and second outputs of the control signal generation unit are connected to the corresponding inputs of the left half-bridge driver, the third and fourth outputs of the control signal generation unit are connected to the corresponding inputs of the right half-bridge driver, at the same time the first and second outputs of each driver are connected to the control the inputs of the corresponding power half-bridges, the upper points of which are connected to the positive terminal of the stepper motor power supply, and the midpoints to the stepper motor winding, while the lower point of the left power half-bridge through the first of the measuring resistor and the lower point of the right power half-bridge through the second measuring resistor are connected to the negative terminal of the stepper motor power supply, the third and fourth inputs of both drivers are connected, respectively, to the positive and negative terminals of the driver power supply, and their third outputs, respectively, to the middle points of the left and right power half-bridges, and the block for generating the current stabilization signal contains a logic element 2I and a logic element 2OR, whose output is the output of the block for generating a current stabilization signal, and the first input of the logic element 2I is the first input of the current stabilization signal generation unit and is connected to the output of the first comparator, the second the input of the current stabilization signal generating unit is connected to the output of the second comparator and the negative terminals of all power sources are connected to each other, characterized in that two adders, three programmable keys, a third comparator, sec th, third and fourth reference voltage sources and the logic gate NOT to the current stabilization signal generation unit, while the additional output of the current stabilization signal generation unit, which is the output of the logic element 2 OR, is connected to the additional input of the control signal generation unit, the output of the logic element 2 OR is connected with the input of the logic element NOT, the output of which is connected to the second input of the logic element 2I, the first input of the logic element 2OR is connected to the second input of the current stabilization signal generating unit, and its second input is connected to the third input of the current stabilization signal generation unit, to which the output of the third comparator, the inverting input of the first comparator is connected to the output of the first software-controlled key, the non-inverting input of the second comparator is connected to the output of the second software-controlled key, and its inverting input is connected to the output of the second reference voltage source, non-inverting the input of the third comparator is connected to the output of the third reference voltage source, and its inverting input is connected to the output of the third software-controlled key, the first and second inputs of the software-controlled keys are connected, respectively, to the outputs of the first and second adders, the first inputs of which are connected to the output of the fourth reference voltage source, wherein the second input of the first adder is connected to the upper terminal of the first measuring resistor, and the second input of the second adder is connected to the upper terminal of the second measuring resistor.

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