【Prize from the Minister of Economic, Trade and Industry】
Lower heat generating, high efficiency stepping motor and
driver package
（AR series）
ORIENTAL MOTOR CO., LTD
Taito-ku, Tokyo, Japan
1.
Overview of the product
Stepping
motors
are
widely
used
in
the
field of
semiconductor
manufacturing and medical industries because they are able to accurately
control the rotation angle and the speed by open-loop control. The demand for
high
speed
and
continuous
operation has been increasing in
order to improve the machine
efficiency. To meet this demand,
the
AR
generating
stepping
series,
“lower
high
motor
heat
efficiency
and
driver
package”, was developed.
By improving the motor and the
driver, power consumption was
reduced by up to 100W and
efficiency was improved by up to
Fig.1
efficiency
Lower heat generation, high
stepping
package (AR series)
motor
and
driver
26%.
Drastically lowering the losses of the motor has enabled continuous
operation that had been previously impossible.
The AR series can be used in wide variety of machines due to a large
selection of models available which includes the standard type with motor
frame size of □ 42mm ~ □ 85mm, maximum holding torque of 0.3Nm ~ 4Nm,
geared type motor, and motors with an electromagnetic brake.
In addition, the AR series are designed for safety and to be environmentally
friendly by complying to UL/CSA standards, CE Marking, and the RoHS
directive in EU.
2. Technical features and advantages
2.1
Technical features
There has been little research and development on stepping motors focusing
on the reduction of losses. This is because the majority of the research has
been focusing on how to produce higher torque because the stepping motor
has been used mainly to utilize the torque at low speed. Also, they have been
recognized as motors that produce massive losses in the principle due to its
structure of many poles.
A big portion of losses of a stepping motor rotating at high speed is iron loss,
and reducing the iron loss is the major issue. For AR series, the following
research and development was conducted by focusing on the iron loss.
(1) Loss reduction by selecting the suitable lamination sheet
Iron loss is generated in the stator and the rotor, which are made of
lamination sheets. Although it is commonly known that the iron loss can be
reduced with the use of low iron loss material, the saturation flux density
tends to decrease as well and this results in smaller torque for the motor. The
selected iron loss has to meet the requirement of minimum torque for a
motor.
(2) Lower iron loss by suitable fastening method
The lamination sheets are given an insulation coating and fastened by
punching dimples into the laminated sheets. The electrical insulation
between the lamination sheets is broken down at these dimples. By
reviewing the fastening method, the AR series utilizes a less insulation
damaging fastening method.
As for the driver of the AR series, a new switching sequence was developed
which is able to reduce the electromagnetic noise. With this development,
switching speed becomes faster and results in reducing both switching loss
and switching noise from the driver.
2.2
Advantages
(1) Energy saving
The input energy and the efficiency of AR69AA-1 (motor frame 60mm,
motor length 90mm, single-phase 100VAC) are compared with a conventional
motor with the same output. They are calculated at the condition of 50% load
because stepping motors are often used at 50% of their maximum torque.
Figure 2 shows the comparison of input energy, and figure 3 shows the
efficiency. The input energy is decreased at all speed range by up to 100W.
The efficiency is increased at all speed range by up to 26%.
300
Input , Out put [W]
250
200
Input decreased
150
100
50
0
0
1000
2000
3000
4000
Speed [r/ min]
AS input
AR input
Fig.2 Input at 50% load
Out put
Efficiency [%], Out put [W]
120
100
80
Efficiency increased
60
40
20
0
0
1000
2000
3000
4000
Speed [r/ min]
AS efficiency
AR efficiency
Out put
Fig.3 Efficiency at 50% load
(2) Economic efficiency
Chart 1 shows the economic efficiency of AR series compared to the
conventional motor. The amount of energy consumption from the operation is
calculated by using the loss as energy consumption. The annual electricity
rate and the CO2 emissions are calculated to be ¥8970 and 249kg respectively.
The use of the AR series brings great advantages in electricity use and the
CO2 emissions. Referring to the guidelines issued from the Semiconductor
Equipment Association of Japan (SEAJ), the economic efficiency on Chart 1 is
calculated with the conditions below.
・Operating conditions: Speed 1000r/min, Load 50%
・Operating time:24hrs (Run 70%, Stand by 25%, Stop 5%) 365days/yr
Chart. 1 Comparison of economic efficiency（Calculation of power losses）
Running wattage [W]
AS*
146
AR
49
98W、 66% Down
Stand by wattage
8.9
7.5
1.4W、16% Down
915
13,725
317
4,755
[W]
Amount of wattage [kWh/yr]
Electricity rate
（Rate: 15 yen/kWh）[yen/yr]
Comparison
598kWh/yr, 65%Down
8,970yen/yr, 65%Down
CO２ emission
381
132
249kg/yr, 65%Down
（Rate 0.416kg/kWh）[kg/yr]
*AS indicates the conventional motor
(3) Others
The lifetime of motors is heavily dependant on the motor temperature.
(Arrhenius equation) By reducing the loss on the motor, heat generation is
reduced which results in longer lifetime. With the longer lifetime, the
required machine maintenance time will also be reduced. The conventional
motor requires cooling time to keep the motor temperature below the
specification due to its characteristic of large heat generation. However, the
AR series is capable of continuous operation and the cooling time is not
necessary which leads to the improvement of productivity. Also a fan is no
longer needed, unlike conventional motors.
3.
Applications
Since the release in August in 2007, the total number of sales exceeded
2500pieces, and is still increasing. Reduction of heat generation and
improvement of machine efficiency are reported from the users in
bookmaking machines, semiconductor manufacturing equipment, logistical
carrier systems, and food processors.