JP6163864B2 - Stepping motor drive unit - Google Patents

Description

  The present invention relates to a unit for driving a stepping motor. In particular, the present invention relates to a stepping motor driving unit provided with a unipolar type two-phase stepping motor, the motor driver for driving the motor, and a cable connecting them.

  Of the stepping motors, many of the unipolar type two-phase stepping motors, as shown in FIG. 1 and FIG. 2, are two pairs of coils (A phase coil 33, AB phase coil 34, B phase coil 35, respectively) wound by bifilar. BB phase coil 36), and each pair of coils is strongly coupled electromagnetically. In the unipolar type two-phase stepping motor, one end of the windings of two pairs of coils is connected internally so that a regenerative current flows in a direction opposite to the pair of coils, and is drawn out of the motor as a common wire There is a 6-wire motor 31 (FIG. 1) and an 8-wire motor 32 (FIG. 2) in which both ends of the windings of two pairs of coils are drawn out of the motor. The 8-wire motor can be regarded as a 6-wire motor if the lead wires drawn from one end of the windings of each pair of coils are connected outside the motor. Some motors have a connector with a connector for connecting the lead wire or cable instead of directly pulling out the lead wire, but the basic configuration is the same. In order to identify the lead wire or connector terminal of the 6-wire unipolar type two-phase stepping motor 31 shown in FIG. 1, each wire or terminal is hereinafter referred to as A phase 101, A phase common 102, AB phase (or A bar phase). ) 103, B phase 111, B phase common 112, and BB phase (or B bar phase) 113. Similarly, the lead wires or connector terminals of the 8-wire unipolar type two-phase stepping motor 32 shown in FIG. 2 are hereinafter also referred to as A phase 101, A phase return 104, AB phase 103, AB phase return 105, B phase 111, These are called B-phase return 114, BB-phase 113, and BB-phase return 115.

  A unipolar type two-phase stepping motor is used in combination with a motor driver controlled by a constant voltage or a constant current, and when controlled by a constant current, control by a PWM method (pulse width modulation method) is often used. The unipolar type two-phase stepping motor and the motor driver are connected by a cable.

An example of a conventional cable used to connect a 6-wire unipolar type two-phase stepping motor and a motor driver is shown in FIGS. In the cable shown in FIG. 3, the insulators 122 include the A phase 101 between the motor driver and the motor, the A phase common 102, the AB phase 103, the B phase 111, the B phase common 112, and the BB phase 113. It is connected with covered electric wires, and the six electric wires are twisted to form one bundle. The cable shown in FIG. 4 is a coaxial cable between A phase 101 of motor driver and motor, A phase common 102, AB phase 103, B phase 111, B phase common 112, and BB phase 113. Connected,
Coaxial cable connecting A phase 101 of motor driver and motor, coaxial cable connecting A phase common 102 of motor driver and motor, and coaxial cable connecting AB phase 103 of motor driver and motor Three, coaxial cable connecting B phase 111 of motor driver and motor, coaxial cable connecting B phase common 112 of motor driver and motor, and connecting BB phase 113 of motor driver and motor 3 coaxial cables
Each is a twisted bundle. The outer conductor of each coaxial cable is connected to the frame ground 121 and serves as a shield.

When the unipolar type two-phase stepping motor is a 6-wire type (FIG. 1), many PWM motor drivers apply a predetermined DC voltage (24V in FIG. 1) to the A-phase common 102 and B-phase common 112 of the motor. When the A phase is excited after being applied, the A phase switching element is turned ON / OFF as shown in the following (A) to (D).
(A) The excitation current flows through the A-phase coil 33 by turning on the A-phase switching element. (B) When the current increases with time and reaches a predetermined current value, when the A-phase switching element is switched from ON to OFF, the current cannot flow through the A-phase switching element. An equal amount of regenerative current flows through the AB phase coil 34.
(C) The regenerative current flowing through the AB phase coil 34 gradually decreases.
(D) When the predetermined time or the remaining time of the ON / OFF cycle has elapsed, the switching element is switched ON again.
In a typical PWM motor driver, ON / OFF is repeated at a period of several tens of microseconds. At the time of acceleration, since the energy supplied from the power source to the stepping motor by the excitation current is made larger than the energy recovered by the regenerative current, the ON time becomes longer than the OFF time. On the other hand, at the time of deceleration, the recovered energy is made larger than the supplied energy, so that the OFF time becomes longer than the ON time.

  Here, when the cable 21 connecting the stepping motor 31 and the motor driver 11 becomes longer, the inductance derived from the cable 21 increases, but the inductance of the cable does not have electromagnetic coupling in the opposite direction to the inductance of the other cables. . Therefore, the magnetic energy stored in the inductance of the cable is not regenerated to other cables when the switching element is turned off and becomes leakage inductance, and a high voltage is applied to the switching element. When a bipolar transistor is used as a switching element, if the CE voltage rises excessively, the junction temperature rises, causing secondary breakdown following primary breakdown, leading to breakdown. When a power MOSFET is used as a switching element, secondary breakdown does not occur and it is excellent in stability, but it is known that an avalanche phenomenon occurs when a voltage higher than the breakdown voltage is applied. Since the avalanche phenomenon occurs only while a large voltage is applied to the switching element, although the duration is short, heat equal to voltage × current × time is generated, and the cell temperature of the power MOSFET locally increases. In power MOSFETs, MOSFETs with a large avalanche resistance are usually used, but when a weakly designed MOSFET is used, if a loss due to avalanche operation is repeated, the deterioration of the semiconductor crystal is accumulated and the avalanche resistance is lowered. In some cases, the parasitic transistor is turned on, and the switching element is destroyed. On the other hand, since the switching element is repeatedly turned on and off at a frequency of several tens of kHz, the total heat generation amount per unit time cannot be ignored. For this reason, there is a problem that if the driver is not sufficiently cooled with respect to the heat generation amount, the temperature rises excessively, leading to early deterioration or destruction.

  According to Non-Patent Document 1, not only the badness of the motor phase coil coupling (the electromagnetic coupling between the A phase coil and the AB phase coil, or the electromagnetic coupling between the B phase coil and the BB phase coil), but also the printed circuit board The circuit pattern and the increase in the lead inductance of the harness coming out of the stepping motor are also considered to cause avalanche loss.

  To prevent the motor driver temperature from rising due to avalanche loss, conventionally, the length of the cable connecting the unipolar two-phase stepping motor and the motor driver is shortened, the drive current is reduced, a heat sink is attached, and ventilation is performed. We have taken measures such as improving it.

Sanyo Semiconductor STK672-640C-E Data Sheet

  In a stepping motor drive unit provided with a unipolar type two-phase stepping motor, a motor driver for driving the motor, and a cable for connecting them, the magnitude of the current for driving the stepping motor is the allowable current of the motor driver. If the upper limit is close, or if the margin for the secondary breakdown of the bipolar transistor in the motor driver or the margin for the avalanche breakdown of the MOSFET is small, in order to make the motor driver operate stably, the drive current is reduced or the voltage is decreased. It is necessary to sufficiently cool the motor driver by suppressing the length, shortening the cable, or using a heat sink.

  Accordingly, an object of the present invention is to provide a stepping motor drive unit provided with a unipolar type two-phase stepping motor, a motor driver for driving the motor, and a cable for connecting the motor driver under conditions close to the upper limit of the rating, An object of the present invention is to provide a highly reliable unit that suppresses heat generation of a motor driver even when the length of the motor driver is long.

  The present invention made in view of the above problems includes the following inventions.

That is, the first aspect of the present invention is:
A unipolar two-phase stepping motor having a pair of A-phase coil and AB-phase coil and a pair of B-phase coil and BB-phase coil, the motor driver for driving the motor, both ends of the two pairs of coils, and the driver A stepping motor drive unit provided with a cable to be connected;
(1) A coaxial cable having a conductor connecting one end of a phase A coil and the driver, and a conductor connecting the other end of the phase A coil and the driver;
(2) a coaxial cable having a conductor connecting one end of an AB phase coil and the driver, and a conductor connecting the other end of the AB phase coil and the driver;
(3) a coaxial cable having a conductor connecting one end of a B-phase coil and the driver, a coaxial cable having a conductor connecting the other end of the B-phase coil and the driver, and (4) a BB phase coil A coaxial cable having a conductor connecting one end and the driver, and a conductor connecting the other end of the BB phase coil and the driver;
It is the said motor drive unit which consists of.

  In the second aspect of the present invention, one end of the A-phase coil and one end of the AB-phase coil, and one end of the B-phase coil and one end of the BB-phase coil are respectively connected in the motor. The motor drive unit according to the first aspect.

The third aspect of the present invention is as follows.
Unipolar type two-phase stepping motor having a pair of A-phase coil and AB-phase coil and a pair of B-phase coil and BB-phase coil, the motor driver for driving the motor, and a conductor drawn from both ends of the two pairs of coils And a stepping motor drive unit provided with a cable connecting the driver and
A conductor drawn from one end of the A-phase coil and one end of the AB-phase coil, and a conductor drawn from one end of the B-phase coil and one end of the BB-phase coil are respectively connected in the motor. And the cable is
(1) A state in which a conductor that is connected only to the other end of the A-phase coil and the driver, one end of the A-phase coil, and one end of the AB-phase coil are connected in the motor. And a conductor connecting the driver to the driver, a conductor connecting only the other end of the AB phase coil to the driver, and one end of the A phase coil; A three-layer coaxial cable in which a conductor connecting the driver and the lead wire drawn out in a state where one end of the AB phase coil is connected in the motor is disposed between the other conductors; and (2) B phase Conductor drawn from only the other end of the coil and a conductor connecting the driver, and lead drawn in a state where one end of the B-phase coil and one end of the BB-phase coil are connected in the motor And the driver And the conductor connection to, and a conductor for connecting the conductive wire drawn from only the other end of the BB-phase coil driver, and one end of the one end and the BB-phase coil of the B-phase coil the motor A three-layer coaxial cable in which a conductor connecting the conductor drawn out in a connected state and the driver is disposed between the other conductors;
It is the said motor drive unit which consists of.

  A fourth aspect of the present invention is the motor drive unit according to any one of the first to third aspects, wherein the motor driver is a pulse width modulation (PWM) motor driver.

  A fifth aspect of the present invention is the motor drive unit according to the fourth aspect, wherein the switching element in the motor driver is a power MOSFET.

  Hereinafter, the present invention will be described in detail.

Cables for connecting both ends of two pairs of coils (a pair of A phase coil and AB phase coil, and a pair of B phase coil and BB phase coil) included in the unipolar type two-phase stepping motor in the present invention to the motor driver ( Hereinafter, simply referred to as the cable of the present invention)
(1) A coaxial cable having a conductor connecting one end of a phase A coil and the driver, and a conductor connecting the other end of the phase A coil and the driver;
(2) a coaxial cable having a conductor connecting one end of an AB phase coil and the driver, and a conductor connecting the other end of the AB phase coil and the driver;
(3) a coaxial cable having a conductor connecting one end of a B-phase coil and the driver, a coaxial cable having a conductor connecting the other end of the B-phase coil and the driver, and (4) a BB phase coil A coaxial cable having a conductor connecting one end and the driver, and a conductor connecting the other end of the BB phase coil and the driver;
It is characterized by consisting of.

Specifically, when the unipolar type two-phase stepping motor is an 8-wire type 32 (FIG. 2),
(1) A coaxial cable having a conductor that connects the A phase 101 of the motor and the A phase 101 of the driver, and a conductor that connects the A phase return 104 of the motor and the A phase return 104 of the driver;
(2) a coaxial cable having a conductor connecting the AB phase 103 of the motor and the AB phase 103 of the driver, and a conductor connecting the AB phase return 105 of the motor and the AB phase return 105 of the driver;
(3) a coaxial cable having a conductor connecting the B phase 111 of the motor and the B phase 111 of the driver, a conductor connecting the B phase return 114 of the motor and the B phase return 114 of the driver, and (4) A coaxial cable having a conductor connecting the BB phase 113 of the motor and the BB phase 113 of the driver, and a conductor connecting the BB phase return 115 of the motor and the BB phase return 115 of the driver;
What is necessary is just to provide the cable which consists of. An example is shown in FIG.

  In FIG. 6, a conductor that connects the A phase 101 of the motor and the A phase 101 of the driver, a conductor that connects the AB phase 103 of the motor and the AB phase 103 of the driver, a B phase 111 of the motor and a B phase 111 of the driver. And a conductor connecting the BB phase 113 of the motor and the BB phase 113 of the driver to the inside (internal conductor), a conductor connecting the A phase return 104 of the motor and the A phase return 104 of the driver, A conductor connecting the AB phase return 105 of the motor and the AB phase return 105 of the driver, a conductor connecting the B phase return 114 of the motor and the B phase return 114 of the driver, and a BB phase return 115 of the motor and the BB phase of the driver The conductors connecting the return 115 are arranged on the outside (external conductor), but the arrangement relationship is reversed (for example, the motor Phase return 104 and the driver conductor for connecting the A-phase return 104 inside the conductor for connecting the A-phase 101 of the motor phase A 101 and driver may be outside). In the coaxial cable, equal currents flow in opposite directions between the inner conductor and the outer conductor.

On the other hand, when the unipolar type two-phase stepping motor is a six-wire type 31 (FIG. 1), one end of the A-phase coil and one end of the AB-phase coil are connected in the motor (A-phase common), and the B-phase coil Because one end of the BB and one end of the BB phase coil are connected in the motor (B phase common),
(1) A coaxial cable having a conductor connecting the A phase 101 of the motor and the A phase 101 of the driver, and a conductor connecting the A phase common 102 of the motor and the A phase common 102 of the driver;
(2) a coaxial cable having a conductor connecting the AB phase 103 of the motor and the AB phase 103 of the driver, and a conductor connecting the A phase common 102 of the motor and the A phase common 102 of the driver;
(3) A coaxial cable having a conductor connecting the B phase 111 of the motor and the B phase 111 of the driver, a conductor connecting the B phase common 112 of the motor and the B phase common 112 of the driver, and (4) A coaxial cable having a conductor connecting the BB phase 113 of the motor and the BB phase 113 of the driver, and a conductor connecting the B phase common 112 of the motor and the B phase common 112 of the driver;
What is necessary is just to provide the cable which consists of. An example is shown in FIG.

In FIG. 5, a conductor that connects the A phase 101 of the motor and the A phase 101 of the driver, a conductor that connects the AB phase 103 of the motor and the AB phase 103 of the driver, a B phase 111 of the motor and a B phase 111 of the driver. And a conductor connecting the motor BB phase 113 and the driver BB phase 113 on the inner side (internal conductor), a conductor connecting the motor A phase common 102 and the driver A phase common 102, and The conductors connecting the B phase common 112 of the motor and the B phase common 112 of the driver are respectively arranged on the outside (external conductors), but the arrangement relationship is reversed (for example, the A phase common 102 of the motor and the A phase of the driver). The conductor connecting the phase common 102 may be on the inside, and the conductor connecting the A phase 101 of the motor and the A phase 101 of the driver may be outside). Furthermore, when the coaxial cable is a cable (three-layer coaxial cable) having a conductor of three layers (inner, intermediate layer, and outer), as shown in FIG.
(1) The conductor connecting the A phase 101 of the motor and the A phase 101 of the driver is inside (internal conductor), and the conductor connecting the A phase common 102 of the motor and the A phase common 102 of the driver is an intermediate layer (intermediate layer). A three-layer coaxial cable in which the conductor connecting the AB phase 103 of the motor and the AB phase 103 of the driver is arranged on the outside (external conductor), respectively, and (2) the B phase 111 of the motor and the B of the driver The conductor connecting phase 111 is inside (internal conductor), the conductor connecting B phase common 112 of the motor and B phase common 112 of the driver is an intermediate layer (intermediate layer conductor), BB phase 113 of the motor and driver A three-layer coaxial cable in which the conductor connecting the BB phase 113 is arranged on the outside (outer conductor),
An embodiment consisting of In the embodiment shown in FIG. 7, the inner conductor and the outer conductor are reversed (for example, the conductor connecting the AB phase 103 of the motor and the AB phase 103 of the driver is inside, and the A phase 101 of the motor and the A phase of the driver are 101 may be outside).

  By the way, when a coaxial cable having three layers of conductors is applied to the 8-wire unipolar type two-phase stepping motor 32 (FIG. 2), four three-layer coaxial cables are used and the outer conductor is connected to the frame ground. What is necessary is just a shield.

The coaxial cable constituting the cable of the present invention is a single-core shielded cable,
An outer conductor (two-layer coaxial cable) insulated from the inner conductor by the inner conductor and insulating layer, or an inner conductor, an intermediate conductor insulated from the inner conductor by the insulating layer, and an outer conductor insulated from the intermediate conductor by the insulating layer (Three-layer coaxial cable),
The cross-sectional area of each conductor may be determined in consideration of the motor drive current. For the insulating layer and the jacket, fluororesins such as ETFE, FET, PFA, and PTFE, polyethylene, and vinyl chloride are used. The inductance, capacitance, and characteristic impedance of a coaxial cable are determined by the outer diameter of the inner conductor and the inner diameter of the outer conductor, and the dielectric constant and permeability of the insulator. In the case of a high-frequency coaxial cable having a characteristic impedance of 50Ω or 75Ω, the outer conductor The ratio of the outer diameter of the inner conductor to the inner diameter is 3 to 6. If the ratio is large, the outer diameter of the cable becomes thicker than the inner conductor having a thickness that allows a predetermined current, which makes it difficult to handle and increases the inductance of the cable. Therefore, when using a two-layer coaxial cable as the coaxial cable constituting the cable of the present invention, the ratio of the inner diameter of the outer conductor to the outer diameter of the inner conductor is preferably between 1.1 and 2.5. More preferably, it is between 1.7. When a three-layer coaxial cable is used as the coaxial cable constituting the cable of the present invention, the ratio of the inner diameter of the intermediate layer conductor to the outer diameter of the inner conductor is between 1.1 and 2.5, and the intermediate layer conductor The ratio of the inner diameter of the outer conductor to the outer diameter is preferably between 1.1 and 2.5, the ratio of the inner diameter of the intermediate layer conductor to the outer diameter of the inner conductor is between 1.1 and 1.7, In addition, it is more preferable that the ratio of the inner diameter of the outer conductor to the outer diameter of the intermediate layer conductor is between 1.1 and 1.7. Such single-core shielded cables (coaxial cables) are manufactured by TEMP-FLEX CABLE, Nikko Electric Wire Co., Ltd., Shinko Electric Wire Co., Ltd., and the like.

  Avalanche loss when a specific cable is used can be evaluated by measuring the output voltage of the driver and the current flowing through the cable, or measuring the temperature of the driver. When two conductors are combined into one as shown in FIG. 5, it can be bundled into one conductor group using soldering or crimping terminals near the both ends of the cable. You may bundle using the wiring pattern on a board | substrate. The cable may be directly connected to the driver or the motor (coil) or may be connected via a connector.

  A pulse width modulation (PWM) motor driver is preferably used as the motor driver provided in the motor drive unit of the present invention because the unipolar two-phase stepping motor can be driven with high power efficiency. As the PWM motor driver, motor drivers having various specifications are commercially available from a plurality of manufacturers such as STK672-640C-E manufactured by Sanyo Semiconductor Co., Ltd. and SLA7080M series manufactured by Sanken Co., Ltd. As a switching element of a motor driver, a power semiconductor such as a bipolar transistor, a field effect transistor (FET), and an insulated gate bipolar transistor (IGBT) can be used. Among them, a power MOSFET having a low on-resistance and a short switching time is preferable. A vertical drain MOSFET (DMOSFET) is particularly preferable.

  In the motor drive unit of the present invention, the lead wires drawn to the outside from both ends of the coil of the stepping motor are often used in a bundled or twisted manner so as not to be separated. However, the excess part may be cut off. Further, it may be bundled by winding a spiral tube or tape so that a gap is not opened between the bundled lead wires or the twisted lead wires. When the lead wires are twisted together, the lead wires drawn from both ends of the A phase coil or the AB phase coil and the lead wires drawn from both ends of the B phase coil or both ends of the BB phase coil are separately twisted. You may match | combine and you may twist together all the said lead wires.

The present invention
A unipolar two-phase stepping motor having a pair of A-phase coil and AB-phase coil and a pair of B-phase coil and BB-phase coil, the motor driver for driving the motor, both ends of the two pairs of coils, and the driver A stepping motor drive unit provided with a cable to be connected;
(1) A coaxial cable having a conductor connecting one end of a phase A coil and the driver, and a conductor connecting the other end of the phase A coil and the driver;
(2) a coaxial cable having a conductor connecting one end of an AB phase coil and the driver, and a conductor connecting the other end of the AB phase coil and the driver;
(3) a coaxial cable having a conductor connecting one end of a B-phase coil and the driver, a coaxial cable having a conductor connecting the other end of the B-phase coil and the driver, and (4) a BB phase coil A coaxial cable having a conductor connecting one end and the driver, and a conductor connecting the other end of the BB phase coil and the driver;
It is characterized by consisting of. According to the present invention, since the loss of the switching element in the motor driver is reduced, the temperature rise can be suppressed even if the heat sink is downsized, and the heat sink can be removed in some cases. As a result, it is possible to reduce the size of the motor driver while improving the reliability and durability of the stepping motor drive unit. Further, the present invention can suppress the temperature increase of the motor driver even if the length of the cable is increased. Therefore, the motor driver can be installed away from the stepping motor, and the degree of freedom in design is improved.

The schematic diagram of the motor drive unit which provided the 6-wire type | mold unipolar type | mold 2 phase stepping motor and the motor driver for the said motor drive. FIG. 3 is a schematic diagram of a motor drive unit provided with an 8-wire unipolar type two-phase stepping motor and the motor driver for driving the motor. The figure which showed an example of the conventional cable provided in a motor drive unit (for 6-wire type | mold unipolar type | mold 2 phase stepping motors). (A) is a side view, (b) is sectional drawing. The figure (sectional drawing) which showed an example of the conventional cable provided in a motor drive unit (for 6 wire type | mold unipolar type | mold 2 phase stepping motors). The figure which showed an example of the cable provided in the motor drive unit of this invention (for 6 wire type | mold unipolar type | mold 2 phase stepping motors). The figure which showed an example of the cable provided in the motor drive unit of this invention (for 8 wire type | mold unipolar type | mold 2 phase stepping motors). The figure which showed an example of the cable provided in the motor drive unit of this invention (for 6 wire type | mold unipolar type | mold 2 phase stepping motors).

  Hereinafter, the present invention will be described in more detail by way of comparative examples and examples using a stepping motor drive unit for moving a dispensing device used in a biochemical analyzer, but these examples limit the present invention. is not.

Comparative Example 1
The AWG20 standard coating as shown in FIG. 3 is applied to PK266-03A manufactured by Oriental Motor Co., Ltd., which is a 6-wire stepping motor, as a unipolar type 2-phase stepping motor, and STK672-640C-E manufactured by Sanyo Semiconductor Co., Ltd. as a motor driver. Using a 1.3 m cable with 6 wires bundled together, the motor lead wire (0.3 m) and the A phase of the driver, A phase commons, AB phases, B phases, B phase commons , BB phases were connected to each other to produce a motor drive unit. The inductance between the A phase and A phase common of this cable was 1.00 μH, and the capacitance was 72 pF.

  PK266-03A was evaluated by reciprocating the dispensing device at a driving current of 3 A, a half step, and a maximum of 4000 PPS. The motor driver was not attached with a heat sink, and the case temperature of the motor driver was measured by attaching a platinum thermometer on the metal surface of the motor driver. As a result of measuring the A-phase output voltage and the A-phase current with an oscilloscope using a voltage probe and a current probe, the duration of the avalanche phenomenon was 136 ns and the avalanche current was 1.22 A. The case temperature of the motor driver was 99 ° C.

Comparative Example 2
As a cable for connecting the stepping motor and the motor driver, as shown in FIG. 4, a coaxial cable 12CX-01 manufactured by TEMP-FLEX CABLE (outer diameter of the inner conductor: 0.96 mm, inner diameter of the outer conductor: 1.09 mm, Evaluation was conducted in the same manner as in Comparative Example 1 except that a 1.3 m cable in which six outer conductors (outer diameter: 1.50 mm) were bundled was used. The inner conductor of each coaxial cable includes the A phase 101 of the motor and the driver, the A phase common 102, the AB phase 103, the B phase 111, the B phase common 112, and the BB phase 113, The frame ground 121 is connected to the outer conductor of each cable. The inductance between the A phase and A phase common of this cable was 0.15 μH, and the capacitance was 4.7 pF.

  As a result, the duration of the avalanche phenomenon was 134 ns, and the avalanche current was 0.96 A. The case temperature of the motor driver was 94 ° C.

Comparative Example 3
The unipolar type two-phase stepping motor was removed and placed near the driver, and the motor lead wire and driver were connected using a 0.11 m cable bundled with six AWG20 coated wires as shown in FIG. Evaluation was conducted in the same manner as in Comparative Example 1. The inductance between the A phase and A phase common of this cable was 0.35 μH, and the capacitance was 325 pF.

  As a result, the duration of the avalanche phenomenon was 96 ns, and the avalanche current was 1.18 A. The case temperature of the motor driver was 91 ° C.

Example 1
As a cable for connecting the stepping motor and the motor driver, as shown in FIG. 5, coaxial cable 12CX-01 manufactured by TEMP-FLEX CABLE (outer diameter of inner conductor: 0.96 mm, inner diameter of outer conductor: 1.09 mm, Evaluation was performed in the same manner as in Comparative Example 1 except that two sets of 1.3 m cables in which two outer conductor outer diameters: 1.50 mm, insulating layer: ETFE, jacket: FEP) were twisted and bundled. The inner diameter of the outer conductor of the coaxial cable is 1.14 times the outer diameter of the inner conductor. Note that the motor and driver A phases 101 and AB phases 103 are connected to the inner conductor of one set of coaxial cables, respectively, and the outer conductors are both A phase of the motor and driver. The commons 102 are connected to each other. Further, the other conductors of the coaxial cables are connected to the B phase 111 of the motor and the driver and the BB phase 113 of the motor, respectively, and the outer conductors are both a B phase common of the motor and the driver. 112 are connected to each other. The inductance between the A phase and A phase common of this cable was 0.35 μH, and the capacitance was 325 pF.

  As a result, the duration of the avalanche phenomenon was 93 ns, and the avalanche current was 0.68 A, which was smaller than those of Comparative Example 1 and Comparative Example 2. Further, the case temperature of the motor driver was 86.5 ° C., which was lower than those of Comparative Example 1 and Comparative Example 2. Furthermore, the temperature was lower than that of Comparative Example 3 using a short cable.

Example 2
As a cable for connecting the stepping motor and the motor driver, as shown in FIG. 7, a coaxial cable 12CX-01 manufactured by TEMP-FLEX CABLE (outer diameter of the inner conductor: 0.96 mm, inner diameter of the outer conductor: 1.09 mm, The outer diameter of the outer conductor: 1.50 mm, the insulating layer: ETFE, the outer cover: FEP) is wound with copper foil (inner diameter of the wound copper foil: 1.99 mm, outer diameter of the wound copper foil: 2.06 mm) In addition, the evaluation was performed in the same manner as in Comparative Example 1 except that two 1.3 m three-layer coaxial cables prepared by covering the outside with a heat-shrinkable tube were used. The inner diameter of the intermediate layer conductor (the outer conductor of the coaxial cable) of the three-layer coaxial cable produced in this example is 1.14 times the outer diameter of the inner conductor, and the inner diameter of the outer conductor (the rolled copper foil) is the intermediate layer. It is 1.33 times the outer diameter of the conductor. Among the two three-layer coaxial cables, the inner conductor of one of the three-layer coaxial cables (the inner conductor of the coaxial cable) is the intermediate layer conductor (the outer conductor of the coaxial cable). Are connected to the A phase common 102 of the motor and the driver, and the outer conductor (rolled copper foil) is connected to the AB phase 103 of the motor and the driver, respectively. The B phase 111 of the motor and the driver is the inner conductor, the B phase common 112 of the motor and the driver is the intermediate layer conductor, and the BB phase 113 of the motor and the driver is the outer conductor. Each is connected. The inductance between the A phase and the A phase common of this cable was 0.22 μH, the capacitance was 744 pF, the inductance between the AB phase and the A phase common was 0.20 μH, and the capacitance was 385 pF.

  As a result, the duration time of the avalanche phenomenon was 103 ns, and the avalanche current was 0.8 A, which was smaller than in Comparative Example 1 and Comparative Example 2. Further, the case temperature of the motor driver was 88 ° C., which was lower than those of Comparative Examples 1 and 2. Furthermore, the temperature was lower than that of Comparative Example 3 using a short cable.

Example 3
As a cable for connecting the stepping motor and the motor driver, as shown in FIG. 5, a shielded one-core cable MVVS 0.18 / 7 × 1C manufactured by Shinko Electric Wire Co., Ltd. (outer diameter of internal conductor: 0.54 mm, external Other than using two sets of 1.3m cables in which conductor inner diameter: 1.25mm, outer conductor outer diameter: 1.50mm, insulation layer: vinyl chloride, jacket: vinyl chloride) Evaluation was conducted in the same manner as in Comparative Example 1. The inner diameter of the outer conductor of the cable is 2.31 times the outer diameter of the inner conductor. The inductance between the A phase and A phase common of this cable was 0.3 μH, and the capacitance was 427 pF.

  As a result, the duration time of the avalanche phenomenon was 120 ns, and the avalanche current was 0.88 A, which was smaller than in Comparative Example 1 and Comparative Example 2. Further, the case temperature of the motor driver was 91 ° C., which was lower than those of Comparative Examples 1 and 2. Furthermore, it was substantially the same temperature as Comparative Example 3 using a short cable.

Example 4
As a cable for connecting the stepping motor and the motor driver, as shown in FIG. 5, a shielded one-core cable ETFE (Y) 19 / 0.203 (manufactured by Nikko Cable Co., Ltd., outer diameter of internal conductor: 1.02 mm, external Other than using two sets of 1.3m cables in which the conductor inner diameter: 1.32mm, outer conductor outer diameter: 1.50mm, insulation layer: ETFE, jacket: ETFE) Evaluation was performed in the same manner as in Example 1. The inner diameter of the outer conductor of the cable is 1.29 times the outer diameter of the inner conductor. The inductance between the A phase and A phase common of this cable was 0.33 μH, and the capacitance was 525 pF.

  As a result, the duration of the avalanche phenomenon was 125 ns, and the avalanche current was 0.70 A, which was smaller than those of Comparative Example 1 and Comparative Example 2. Further, the case temperature of the motor driver was 89 ° C., which was lower than those of Comparative Examples 1 and 2. Furthermore, the temperature was lower than that of Comparative Example 3 using a short cable.

  According to the present invention, it is possible to provide a stepping motor drive unit with low heat generation and high reliability. For this reason, it can be said that it is particularly preferable as a motor drive unit installed in an automatic analyzer such as a biochemical analyzer, in which high reliability is required and a large number of drive units are mounted. Furthermore, according to the present invention, since the driver's heat generation can be suppressed even when the cable is lengthened, the driver can be installed away from the stepping motor. For this reason, the freedom degree of design can be improved.

11: Two-phase stepping motor driver 12: Phase excitation control circuit 13: Power MOSFET
14: Current detection resistor 21: Cable 31: Two-phase unipolar stepping motor with 6-wire specification 32: Two-phase unipolar stepping motor with 8-wire specification 33: A-phase coil 34: AB-phase coil 35: B-phase coil 36: BB-phase coil 101: A phase 102: A phase common 103: AB phase 104: A phase return 105: AB phase return 111: B phase 112: B phase common 113: BB phase 114: B phase return 115: BB phase return 121: Frame ground (FG)
122: Insulator

Claims (5)

A unipolar two-phase stepping motor having a pair of A-phase coil and AB-phase coil and a pair of B-phase coil and BB-phase coil, the motor driver for driving the motor, both ends of the two pairs of coils, and the driver A stepping motor drive unit provided with a cable to be connected;
(1) A coaxial cable having a conductor connecting one end of a phase A coil and the driver, and a conductor connecting the other end of the phase A coil and the driver;
(2) a coaxial cable having a conductor connecting one end of an AB phase coil and the driver, and a conductor connecting the other end of the AB phase coil and the driver;
(3) a coaxial cable having a conductor connecting one end of a B-phase coil and the driver, a coaxial cable having a conductor connecting the other end of the B-phase coil and the driver, and (4) a BB phase coil A coaxial cable having a conductor connecting one end and the driver, and a conductor connecting the other end of the BB phase coil and the driver;
The motor drive unit comprising: The motor according to claim 1, wherein one end of the A-phase coil and one end of the AB-phase coil, and one end of the B-phase coil and one end of the BB-phase coil are connected in the motor. Drive unit. Unipolar type two-phase stepping motor having a pair of A-phase coil and AB-phase coil and a pair of B-phase coil and BB-phase coil, the motor driver for driving the motor, and a conductor drawn from both ends of the two pairs of coils And a stepping motor drive unit provided with a cable connecting the driver and
A conductor drawn from one end of the A-phase coil and one end of the AB-phase coil, and a conductor drawn from one end of the B-phase coil and one end of the BB-phase coil are respectively connected in the motor. And the cable is
(1) A state in which a conductor that is connected only to the other end of the A-phase coil and the driver, one end of the A-phase coil, and one end of the AB-phase coil are connected in the motor. And a conductor connecting the driver to the driver, a conductor connecting only the other end of the AB phase coil to the driver, and one end of the A phase coil; A three-layer coaxial cable in which a conductor connecting the driver and the lead wire drawn out in a state where one end of the AB phase coil is connected in the motor is disposed between the other conductors; and (2) B phase Conductor drawn from only the other end of the coil and a conductor connecting the driver, and lead drawn in a state where one end of the B-phase coil and one end of the BB-phase coil are connected in the motor And the driver And the conductor connection to, and a conductor for connecting the conductive wire drawn from only the other end of the BB-phase coil driver, and one end of the one end and the BB-phase coil of the B-phase coil the motor A three-layer coaxial cable in which a conductor connecting the conductor drawn out in a connected state and the driver is disposed between the other conductors;
The motor drive unit comprising: The motor drive unit according to claim 1, wherein the motor driver is a pulse width modulation (PWM) motor driver. The motor drive unit according to claim 4, wherein the switching element in the motor driver is a power MOSFET.

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