JPS63294297A - Winding current regeneration for unipolar step motor - Google Patents

Abstract

PURPOSE:To improve the winding current regeneration efficiency of a unipolar step motor, by inserting a backward flow blocking diode to each capacitor in series as well as providing multiple capacitors in parallel. CONSTITUTION:When an A-phase exciting transistor Tr 2 is switched OFF from ON, it comes in a regenerating state. As shown in dotted line in the figure, the regenerative current flows in proportion to the counter-electromotive force generated to the A-phase winding through a diode D5, an A-phase winding and a diode D1 and is charged to power capacitors C2 of B-phase and B'-phase. In the presence of a backward flow blocking diode D9, the A- and A'-phase regenerative current is prevented from flowing backward to the A- A'-phase DC current power source section. No A- and A'-phase regenerative currents are refluxed to the same A- and A'-phase constant current controlling transistor Tr 1 but all the currents are efficiently regenerated by the capacitor C2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a winding current regeneration system for a unipolar step motor, and particularly to one that can improve regeneration efficiency.

[Prior Art] A drive circuit for a conventional unipolar stepping motor is shown in FIG. Here, the diode rectifier circuit D7 and the capacitor C constitute a DC circuit section, which rectifies and smoothes the AC voltage AC to obtain a DC power supply voltage. Transistors Tr2, Tr3 . Tr5. Tr6 is a phase excitation transistor, and is turned on in response to an excitation pulse for each phase given from the phase excitation control circuit 2 at a predetermined timing. Transistors Tri and Tr4 provided between the positive terminal of the capacitor C and each winding are constant current control switching transistors. Phase excitation 1 to transistor Tr2. Tr3. Tr5. Current detection resistors R1 and R2 are provided between the Tr6 and the ground. Constant current control circuits 1a and lb detect currents flowing through resistors R1 and R2, and depending on this detection, transistors Tri and Tr
By controlling the base voltage applied to the transistors Tr4, the current flowing through the windings between the emitters and collectors of the transistors Tri and Tr4 is controlled to be a constant current.

Constant current control 1 to transistor Tri, diode D5 provided between Tr4 and ground. D6 is a flywheel diode. Further, a circuit including diodes D1 to D4 and resistors R3 to R6 provided between each winding and the positive terminal of the capacitor C is a regeneration circuit.

The operation of phase A will be explained. When a phase excitation pulse is applied to the base of the transistor Tr2 from the phase excitation control circuit 2, the transistor Tr2 becomes conductive, and as shown by the solid arrow in the figure, the Tri and A phase windings.

Tr2. A winding excitation current flows through R1. During this time,
The constant current control switching transistor Tr1 has its conduction controlled by the output of the constant current control circuit 1a, and controls the winding excitation current to be a constant current. When the transistor Tri is turned off, the flywheel diode D5 causes T r 2 as shown by the dashed-dotted arrow in the figure.
, R1, D 5 .

A freewheeling loop is constructed through the A phase winding to retain the winding power.

When the transistor Tr2 is turned off, a regenerative state is entered. In this regenerative circuit, as shown by the dotted line arrow in the figure, the back electromotive force generated in the A-phase winding is caused to flow as a regenerative current through the diode D 5 HA-phase winding, the diode D1° and the resistor R3.

The above is an explanation of the operation of the A phase, but the other phases operate in exactly the same manner.

By the way, the reason why the resistors R3 to R6 are provided in the regeneration circuit is as follows. In the regenerative state,
The current detected through the excitation current detection resistors R1 and R2 is zero, so Trl and Tr4 are in a conductive state. Therefore, if the resistor R3 were not provided, the regenerative current would flow back through Di and Trl and would not be regenerated to the capacitor C. In order to prevent this, a method is adopted in which resistors R3 to R6 with relatively large resistance values are inserted into the regeneration circuit for each phase to consume the current.

[Problems to be Solved by the Invention] Therefore, in the conventional unipolar step motor drive circuit, it has been impossible to achieve large current and high torque due to the presence of a relatively large resistance in the regeneration circuit. Further, by using a resistor with a large resistance value, the back electromotive force spike voltage also increases, so there is a problem that the constant current control transistor etc. must also be of a high voltage withstand voltage that can withstand it. Furthermore, the heat generated by the resistor requires a cooling fan, making it difficult to downsize the power supply section.

The present invention has been made in view of the above-mentioned points, and is intended to provide a winding current regeneration system for a unipolar step motor that increases current regeneration efficiency by omitting a resistor in a regeneration circuit.

[Means for Solving the Problems] A winding current regeneration system for a unipolar step motor according to the present invention includes at least two capacitors provided in parallel in a power supply circuit, and one of the capacitors connected to a power supply bus. A winding excitation circuit corresponding to at least one connected I-11, and a winding excitation circuit corresponding to a phase different from the I-11 connected to the power supply bus to another one of the capacitors. Each of the winding excitation circuits includes a current regeneration circuit, and each of the current regeneration circuits is connected to a power supply bus of the winding excitation circuit corresponding to the current regeneration circuit. The circuit is wired so that the regenerative current flows through another capacitor, and each of the capacitors is provided with a backflow prevention diode 1~ in series, so that the regenerative current regenerated through each capacitor is connected to the other capacitor. This device is characterized in that it prevents backflow to the winding excitation circuit connected to the capacitor.

[Operation] When exciting a phase (assuming it is A phase), the winding excitation circuit corresponding to that phase is connected to a capacitor connected to the power supply bus of the winding excitation circuit (this is assumed to be the first Power is applied from the power supply circuit via a capacitor (called a capacitor).

The current regeneration circuit provided in this A-phase winding excitation circuit is connected to a capacitor (temporarily referred to as a second capacitor) that is different from the first capacitor, and the regenerative current is transferred to the second capacitor. be swept away by At this time, a reverse current prevention diode is provided in series with each capacitor to prevent the regenerative current from flowing backward into other capacitors and the winding excitation circuit connected thereto. The regenerative current is regenerated to the second capacitor that supplies power to another summation winding excitation circuit, and is not regenerated to the first capacitor that supplies power to the A phase itself. Additionally, the A-phase regenerative current is prevented from flowing back into the A-phase winding excitation circuit. On the other hand, a regenerative current of another phase (for example, B phase) is regenerated to the first capacitor by a similar effect.

In this way, by arranging multiple capacitors in parallel and inserting a backflow prevention diode in series with each capacitor, each capacitor becomes an independent DC power supply, and the regenerative current of each phase is used as a capacitor that supplies power to that phase. It is characterized by being regenerated to a separate capacitor.

This eliminates the need for the regenerative current of each phase to flow back into the winding excitation circuit of its own phase, eliminating the need for a conventional resistor in the regenerative circuit and eliminating all the drawbacks of the conventional method. Can be done. At the same time, regeneration efficiency can be increased.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention in a unipolar step motor having T phases at A, B, and - similar to FIG. 2. In the figure, circuit elements having the same reference numerals as the circuit elements in FIG. 2 perform the same functions.

The A-phase winding excitation circuit is a transistor ']' r I
.

Tr2. A main excitation circuit along the path shown by the solid line arrow in the figure including the resistor R1, a freewheeling circuit along the path shown by the dashed-dotted line arrow in the figure including the flywheel diode D5, and a diode D5.Di. and a regeneration circuit along the route indicated by the dotted line arrow in the figure.

Similarly, the W-phase winding excitation circuit is T r 1 , T”
r.3, a main excitation circuit including R1, and Tr3. R1,D
5 and a diode +: D5 and I]2
It consists of a regeneration circuit including.

Similarly, the B-phase winding excitation circuit has T'r4. Tr5, R
2 and a main excitation circuit including T r 5 , R2, I) 6
and a regeneration circuit including diodes D6 and D4.

Similarly, the W-phase winding excitation circuit has T” r 4 , T
r6, a main excitation circuit including R2, and Tr6. R2, D6
and a regeneration circuit including diodes D6 and D3.

In the power supply circuit, two capacitors C1 and C2 are provided in the σ series of the rectifier circuit D7, and backflow prevention diodes D8, . D9 is provided respectively. Diode D8. D9 is connected with forward polarity to the DC power supplied from the rectifier circuit 1)7.

Power bus line al of the A-phase and A-phase winding excitation circuits.

a2 is connected to a capacitor C1, and the voltage between the terminals of the capacitor C1 is applied to the winding excitation circuit as a DC power supply voltage. The positive bus a1 is connected between the positive terminal of the capacitor C and the cathode of the diode D8, and the ground bus a2 is connected to the negative terminal of the capacitor C1.

On the other hand, the power supply buses bl and b2 of the B-phase and -"o'-+u winding excitation circuits are connected to a capacitor C2, and the voltage between the terminals of the capacitor C2 is applied to the winding excitation circuit as a DC power supply" voltage. applied. The positive bus b1 is connected between the positive terminal of the capacitor C2 and the cathodes of diodes 1 to 9, and the ground bus b2 is connected to the negative terminal of the capacitor C2.

The cathodes of the diodes Di and D2 of the A-phase and W-phase regeneration circuits are commonly connected, and are connected to the power supply capacitor C2, which is connected to the connection point of the diode D9 and the capacitor C2. The regenerative current is the capacitor C
It is designed to be regenerated into 2.

On the contrary, diode + of the regeneration circuit of B, ij- phase: D3
.

D4 has its cathode commonly connected, and the diode D
8 and the connection point of capacitor C1. As a result, the B,]-3 phase regeneration circuit is connected to the A, A phase power supply capacitor C1, and the B, B phase regenerative current is regenerated to the capacitor C1.

In Fig. 1, the excitation operation and reflux operation of each phase are
This is the same as the case shown in the figure.

The regeneration operation according to the present invention will be explained using A4'11 as an example. When the phase excitation transistor 1r2 is switched from on to off, a regenerative state is entered. As shown by the dotted line in the figure, the diode D5. A regenerative current corresponding to the back electromotive force generated in the A-phase winding flows through the A-phase winding and the diode D1, and the B-phase and I-phase power supply capacitors C2 are charged.

The existence of the backflow prevention diode D9 prevents the regenerative current of the A and A phases from flowing backward into a portion of the A-phase and -1-phase DC power supply 11. Therefore, the regenerative currents of A and W phases are the same.

A state in which the current flows back to the W-phase constant current control 1-run transistor Tri does not occur, and all of the current is efficiently regenerated to the capacitor C2.

Further, when the counter electromotive force is regenerated as a regenerative current in the capacitor C2, the regenerated electrical energy is added to the power supply voltage supplied via the diode 9. This electrical energy is discharged when the B phase or 1 phase is excited, so the rotor (
It is expected that the rotor's vertical characteristics will be improved, and therefore the motor can be made to run at higher speeds.

The above is a description of the regeneration operation of the A phase, but the same applies to the other phases.

Note that the number of phases of the step motor and the number of winding excitation circuits corresponding to each phase are not limited to the embodiment shown in FIG.

Further, the number of capacitors is not limited to two, but may be more than two, and can be increased as the number of phases increases.

However, the objectives of the invention can be achieved using at least two capacitors.

In addition, the DC supply circuit of the power supply section including the diode D7 is
It does not have to be the same as this embodiment, and other circuit configurations may be used as long as the rated power of the motor can be supplied via the backflow prevention diodes D8 and D9.

[Effects of the Invention] As described above, the present invention provides the following various effects.

(1) Since the back electromotive force generated in each phase winding of the unipolar step motor can be efficiently regenerated, power efficiency is increased.

(2) Accordingly, high-voltage power can be supplied at the rise of the winding excitation current, making it possible to increase the speed.

(3) Since the regeneration efficiency is good, the winding current is rapidly attenuated, the braking torque of the rotor is also reduced, and high speed can be expected.

(4) Furthermore, since no special resistance is inserted in the regeneration circuit to limit the current, high voltage spikes that would otherwise occur due to the insertion of the resistance are not generated.

Furthermore, since there is no need for a high-voltage constant-current limiting one-herald transistor, the voltage-resistant design is easy and costs can be reduced.

(5) Furthermore, since no heat loss occurs due to the memory resistor, power efficiency is good, and therefore a cooling fan is not required, making it possible to downsize the power supply unit.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a drive circuit for a unipolar step motor employing the winding current regeneration method according to the present invention, and FIG. 2 is a circuit diagram showing an example of a drive circuit for a conventional unipolar step motor. This is a circuit diagram. ia, lb... Constant current control circuit, 2/phase excitation control circuit, Trl, Tr4/constant current switching control 1 helangister, T r 2r T r 3 r T r 5 r
'1. ” r 6-・+11 excitation switching drive transistor, I) 1.D2゜D3.D4...Regeneration diode, 1-5.D6...Flywheel diode, D
7. Rectifier circuit diode, D8. D9...Reverse current prevention diode, C2C1, C2 power supply capacitor, R1,
R2...Current detection capacitor, R3, R4, R5,
R6...Resistance. Applicant Hitachi Electronics Engineering Co., Ltd. Agent
Patent Attorney Yoshihito Iizuka Diagram 2 (previously with 0 branches)

Claims (2)

[Claims] (1) At least two connected in parallel in a power supply circuit
a winding excitation circuit corresponding to at least one phase having a power bus connected to one of the capacitors; and a winding excitation circuit corresponding to at least one phase having a power bus connected to another one of the capacitors; and a winding excitation circuit corresponding to the phase, each of the winding excitation circuits each including a current regeneration circuit, and each of the current regeneration circuits having a winding excitation circuit corresponding to the current regeneration circuit of the capacitor. The circuit is wired so that the regenerative current flows through a capacitor other than the capacitor to which the power supply bus is connected, and a backflow prevention diode is provided in series with each of the capacitors, so that the regenerative current flows through each capacitor. A winding current regeneration system for a unipolar step motor, characterized in that the regenerative current is prevented from flowing back into the winding excitation circuit connected to another capacitor. (2) The winding current of the unipolar step motor according to claim 1, wherein the plurality of backflow prevention diodes corresponding to the plurality of capacitors are inserted with a forward polarity with respect to the power supply direct current. Regeneration method.