JP2854033B2 - Micro-step driving device for 5-phase stepping motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Field of the Invention The present invention relates to a micro-step drive device for a five-phase stepping motor that subdivides one step angle of a five-phase stepping motor.

b. Prior Art A stepping motor is generally operated at a basic step angle θ _s or half thereof, but can be further divided by controlling the winding current.
Such multi-division by current control is generally called micro-step driving.

c. Problems to be Solved by the Invention In such a control method, it was necessary to control the current of each phase independently. This complicates the circuit configuration, such as requiring a current chopper circuit for each phase.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems and to provide a micro-step driving device for a five-phase stepping motor capable of performing micro-step driving with a simple configuration.

d. Means for Solving the Problems The configuration of the present invention for achieving the above object is a stepping motor in which each phase winding is connected in a ring shape, and five series circuits including a pair of switching elements connected in series with each other. And a drive circuit that configures a polyphase inverter by connecting the connection points of the pair of switching elements to the connection points of the phase windings, turning on and off the pair of switching elements. A current command generation unit that receives a command pulse and generates a current command value for each phase output from the inverter in a micro-step drive device of a five-phase stepping motor that turns off and allows a current to flow through each phase winding. And the current of each phase output from the inverter is detected by the detecting means, and the detected current value is always detected by the current command generator for each phase. A current control unit that controls the current command unit to match the current command value, and a PWN gate pulse generation circuit that outputs a gate pulse to a switching element of the inverter based on a signal from the current control unit. The current command value for each phase from is a triangular waveform distorted AC signal having a phase difference of 2π / 5, and the distorted AC signal is obtained by equally dividing one cycle of any given signal into ten. When 1 is a certain value, the first two sections monotonically increase from 0 to 1, the next two sections monotonically decrease from 1 to 0, and the next one section is 0, and The two sections monotonically decrease from 0 to 1 and the next 2
The section monotonically increases from -1 to 0, and the last section is 0
And the sum of the current command values is zero.

In addition, the present invention connects a stepping motor in which each phase winding is connected in a star shape and five series circuits including a pair of switching elements connected in series to each other in parallel,
A driving circuit that forms a polyphase inverter by connecting a connection point of each of the pair of switching elements to a connection point of each of the phase windings, turning on and off each of the pair of switching elements, In a micro-step driving device for a five-phase stepping motor for flowing a current through a winding, a current command generating unit that receives a command pulse and derives a current command value for each phase output from the inverter; A current control unit for controlling the current of each phase to be detected by the detection means, and controlling the detected current value to always match the current command value for each phase from the current command generation unit. A PWM gate pulse generation circuit that outputs a gate pulse to the switching element of the inverter based on a signal from the current control unit. Are the trapezoidal waveform distorted AC signals each having a phase difference of 2π / 5, and the distorted AC signal has 1 when any one cycle of the signal is divided into ten equal parts. Constant value, the first two sections are -1
From 1 to 1, the next 3 sections are 1 and the next 2 sections are monotonically decreasing from 1 to −1, and the last 3 sections are −1. That is, the sum of the current command values is zero.

e. Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a hybrid type five-phase stepping motor in which each phase winding is connected in a ring shape. 2
Is a drive circuit connected to each phase winding of the five-phase stepping motor 1. This drive circuit 2 is an inverter circuit formed by connecting five sets of switching elements S ₁ ... S ₁₀ connected in series each two of which are connected to a common DC electrode E. Each of these pairs of switching elements S ₁
Connection points a... E of S ₂ , S ₃ and S ₄ , S ₅ and S ₆ , S ₇ and S ₈ , S ₉ and S ₁₀ are ring (pentagon) connection, connection of each phase winding Aφ. In the case of the star-shaped (star) connection shown in FIG. 2, they are connected to the connection points a 'to e' of the phase windings Aφ to Eφ. Reference numeral 3 denotes a current command generator which receives a command pulse from the pulse oscillator and generates a command value of a current output from an inverter constituting the drive circuit 2; current control unit for controlling a command value as from the, 5, the switching element S ₁ ... S ₁₀ of the inverter based on a signal from said current control unit 4
Is a PWM gate pulse generation circuit that outputs a gate pulse to the gate. The current control unit 4 detects each phase current value output from the polyphase inverter, and when the current value deviates from the command value from the current command generating unit 3 due to a change in impedance of the motor winding. Is to correct the deviation and to control the current value output from the multi-phase inverter to always be the same as the command value from the current command generator 3.

Each phase current command value is, as shown in FIG.
The current command value is a distorted alternating current of a triangular waveform with each phase having a phase difference of 2π / 5. If one cycle of the waveform of an arbitrary phase is divided into 10 equal parts, 1 is a constant value and the first two sections Is 0 to -1
Monotonically increases, and monotonically decreases from -1 to 0 in the next two sections. The next one section is set to 0 command, the next two sections monotonically decrease from 0 to 1, the next two sections monotonically increase from 1 to 0,
The last one section is a current waveform constituting one cycle as 0 command, and the sum of each current command value is 0.

Each phase current command value is a trapezoidal distorted AC having each phase having a phase difference of 2π / 5 as shown in FIG.
When one cycle of a waveform of an arbitrary phase is divided into ten equal parts, 1 is a certain value, and the first two sections monotonically increase from −1 to 1,
The next three sections keep 1 and the next two sections monotonically decrease from 1 to -1. The last three sections are -1 and the sum of the current command values is zero.

 Next, the operation of the above embodiment will be described.

The expression of the torque of each phase of the five-phase stepping motor is as follows.

Each phase torque generated by currents i _{A to} i _E flowing in each phase
The combined value of T _A , T _B , T _C , T _D , and T _E (where K _T is a constant in the above equation) is the total generated torque, and a torque vector diagram when each phase is driven by a constant current Is T0 shown in FIG.
Indicated by ~ T10. (However, this figure shows four-phase excitation.) The excitation sequence at this time is shown in FIG. Therefore, by performing the five-phase excitation, the resolution can be improved only up to the half-step angle which is half the full-step angle. Here, by controlling the current
Consider generating a vector of T0-N.

T0 is _{i A = i, i C =} -i, i d = -i, i E = i, a vector generated as i _g = 0, T1 is i _E = 0 from the state T0, i _B = i Is a vector generated by Vector of T0-N by controlling the magnitude of i _B and i _E, the i _E to be a vector of T _E → T _E 'in Figure 5 monotonically decreasing from i, T _B as T _B 'If halted by the current value to generate a monotonously increased so T0-N vector i _B to generate a vector, can be stopped at a step angle from T0 theta _N. That is, the command current value is divided into M equal parts, and each of i _E and i _B is divided into M equal parts each time an input pulse is input,
By decreasing monotonically and increasing monotonically, M between T0 and T1 becomes M
It can be divided into equal steps. FIG. 4 shows a phase current waveform obtained by calculating the current flowing through each phase. This current waveform is a balanced polyphase alternating current, and the current can be controlled by a half-bridge type inverter. In the case of the star connection shown in FIG. 2, the output current of the inverter coincides with the phase current obtained above, and microstep driving can be realized by directly using the current waveform in FIG. 4 as the designated waveform.

In the pentagon connection shown in FIG. 1, the phase current and the inverter current waveform do not match, and the command current waveform needs to be a triangular wave-shaped current instruction value shown in FIG. 3 in order to flow the phase current shown in FIG. There is.

f. Effects of the Invention As described above, the microstep driving device for a five-phase stepping motor according to the present invention has the following effects.

Since the output current of the inverter is detected independently for each phase and the current is controlled independently for each phase based on the result, it is necessary to subdivide the step angle by one step compared to the conventional micro-step drive of a five-phase stepping motor. Can be.

Conventionally, in the micro-step drive of a five-phase stepping motor, 20 elements were required for expensive power switching, but according to the present invention, only half the number was required, and the gate circuit of the power element was included. The circuit can be greatly simplified. In addition, especially in the case of microstep drive, high-speed switching is required, and in many cases, FETs are used as power elements. In this case, it is generally necessary to electrically insulate the + side element and the gate, reducing the number of power elements by half Great effect. Further, the driving device of the present invention is a half-bridge inverter, and has five outputs and can simplify the connection. With conventional micro-step drive
With 10 wires, it can greatly contribute to simplifying work and preventing incorrect connections.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a micro-step driving device for a five-phase stepping motor according to the present invention, FIG. 2 is a circuit diagram showing a driving circuit when each phase winding of the stepping motor is star-connected, 3 is a waveform diagram showing a current command in the case of ring connection, FIG. 4 is a waveform diagram showing a current command in the case of star connection, and FIG. 5 is a torque vector diagram when each phase is driven by a constant current. FIG. 6 is a waveform diagram showing the excitation sequence. 1 ... hybrid type 5-phase stepping motor 2 ... drive circuit 3 ... current command generator 4 ... current controller 5 ... PWM pulse generator S ₁ ... S ₁₀ switching element Aφ ... Eφ ... Each phase winding.

Claims (2)

(57) [Claims] 1. A stepping motor in which each phase winding is connected in a ring shape and five series circuits each including a pair of switching elements connected in series with each other are connected in parallel, respectively, and a connection point of each of the pair of switching elements is set. A drive circuit connected to a connection point of each of the phase windings to form a polyphase inverter; turning on and off each of the pair of switching elements to flow a current through each of the phase windings; In the micro step drive device, a current command generating unit that receives a command pulse and generates a current command value for each phase output from the inverter, and a current of each phase output from the inverter is detected by a detection unit. A current control unit for detecting each of the detected current values and controlling the detected current values to always correspond to the current command value for each phase from the current command generation unit; PW for outputting a gate pulse to the switching element of the inverter based on a signal from the Department
An M gate pulse generation circuit, wherein the current command value for each phase from the current command generator is a triangular waveform distorted AC signal having a phase difference of 2π / 5, and the distorted AC signal Is, when one cycle of any given signal is divided into 10 equal parts,
Let 1 be a fixed value, the first two sections monotonically increase from 0 to 1, the next two sections monotonically decrease from 1 to 0, and the next one section is 0, and the next two sections Is a signal waveform that monotonically decreases from 0 to −1, increases monotonically from −1 to 0 in the next two sections, and is 0 in the last section, and the sum of the current command values is A micro-step driving device for a five-phase stepping motor, wherein 0 is set. 2. A stepping motor in which phase windings are connected in a star shape, and five sets of series circuits each comprising a pair of switching elements connected in series with each other are connected in parallel, respectively, and a connection point of each of the pair of switching elements is connected. And a drive circuit that constitutes a polyphase inverter by connecting to a connection point of each of the phase windings, and turns on and off the pair of switching elements and causes a current to flow through each of the phase windings. In the motor microstep drive device, a current command generating unit that receives a command pulse and generates a current command value for each phase output from the inverter, and detects a current of each phase output from the inverter. A current control unit for controlling each of the detected current values to always match a current command value for each phase from the current command generation unit; PW for outputting a gate pulse to the switching element of the inverter based on a signal from the Department
An M gate pulse generation circuit, wherein the current command value for each phase from the current command generator is a trapezoidal waveform distorted AC signal having a phase difference of 2π / 5, and the distorted AC signal Is, when one cycle of any given signal is divided into 10 equal parts,
Let 1 be a constant value, the first two sections monotonically increase from -1 to 1, the next three sections are 1, and the next two sections are 1 to-
A microstep driving device for a five-phase stepping motor, wherein the signal waveform monotonically decreases to 1 and the last three sections are set to −1, and the sum of the current command values is 0. .