Electric power conversion systems – Current conversion – Including an a.c.-d.c.-a.c. converter
Reexamination Certificate
1995-06-06
2002-01-01
Vu, Bao Q. (Department: 2838)
Electric power conversion systems
Current conversion
Including an a.c.-d.c.-a.c. converter
C363S037000
Reexamination Certificate
active
06335871
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a motor operation controller and an insulation type bidirectional DC voltage converter for accommodating different power supply voltages.
2. Description of Prior Art
Power supply voltages to a motor operation controller vary substantially depending on the application of a motor and the country or region where the motor is used. For example, in Japan, generally the home power supply voltage is 100 VAC, while the industrial power supply voltage is 200 VAC. In overseas countries, the industrial power supply voltages are 200-230 VAC, 380 VAC, 400 VAC, and 415 VAC (Europe) and 240 VAC and 460-480 VAC (USA). Generally, the industrial power supply voltages are roughly classified into 200 VAC, 240 VAC, 380 VAC, 415 VAC, and 480 VAC.
The motor is used in any operation state of acceleration, normal output, and deceleration. Thus, the motor operation controller requires two functions of feeding energy to the motor from an input power supply, which will be hereinafter referred to as a “power mode,” and of returning rotation energy of the motor and a rotor secured to the motor to the input power supply by operating the motor as a generator, which will be hereinafter referred to as a “regeneration mode.”
FIG. 28
is a block diagram showing the main circuit part of a conventional motor operation controller, wherein numeral
1
is an input power supply, numeral
2
is a motor operation controller, and numeral
3
is a motor. The motor operation controller
2
is roughly divided into a converter section
4
for converting an AC input section and a DC. section bidirectionally and an inverter section
5
for converting DC into AC. In the converter section
4
, numeral
6
is a rectifier made up of a diode bridge, etc., numeral
7
is a power supply inverter made up of a transistor bridge, etc., for outputting a power supply frequency, numeral
8
is a power supply inverter controller for controlling the operation of the power supply inverter
7
, and numeral
9
is a smoothing circuit made up of an electrolytic capacitor, etc. In the inverter section
5
, numeral
10
is an inverter for outputting a voltage, current, and frequency in response to the operation state of the motor
3
, numeral
11
is an inverter controller for controlling the operation of the inverter
10
, and numeral
12
is an interface circuit for receiving operation commands of the motor
3
, such as acceleration, deceleration, and rotation speed, given from the outside.
FIG. 29
is a conventional example for accommodating power supply voltages incompatible with the voltage specifications of the motor operation controller
2
and the motor
3
, wherein numeral
1
a
is an input power supply incompatible with the voltage specifications and numeral
13
is a transformer for converting a power supply voltage incompatible with the voltage specifications into a voltage conforming to the specifications.
FIG. 30
is a connection example involving a plurality of motor operation controllers
2
a
,
2
b
, and
2
c
and a plurality of motors
3
a
,
3
b
, and
3
c
. In the example, batch voltage conversion is made through the transformer
13
for supply to the motor operation controllers
2
a
,
2
b
, and
2
c
. The motor operation controllers
2
a
,
2
b
, and
2
c
receive motor operation commands a, b, and c, respectively, from the outside.
FIG. 31
is a circuit diagram shown in Japanese Patent Laid-Open 4-38192, wherein a DC voltage converter
20
is provided between a rectifier
6
in a converter section and an inverter section
5
for accommodating power supply voltages incompatible with the voltage specifications of the motor
3
. In
FIG. 31
, numeral
21
is a primary smoothing circuit, numeral
22
is a secondary smoothing circuit, numeral
23
is a discharge resistor, numeral
24
is a discharge switch, and numeral
25
is a controller for controlling the DC voltage converter
20
and the inverter section
5
.
Next, the operation will be discussed. First, the operation of the motor operation controller
2
in
FIG. 28
will be described. In the power mode, the motor operation controller
2
converts an input AC voltage
1
into a DC voltage through the rectifier
6
and smooths the DC voltage by the smoothing circuit
9
. Then, it again converts the smoothed DC voltage into an AC power supply of a voltage, current, and frequency required for operating the motor
3
by the inverter
10
. When receiving an output of the inverter section
5
, the motor is operated at a predetermined rotation speed. Next, in the regeneration mode, the inverter
10
operates so as to run the motor
3
as a generator. As a result, rotation energy of the motor
3
is fed back through the smoothing circuit
9
via the power supply inverter
7
to the input power supply
1
, applying an electric brake. The inverter controller
11
controls the inverter
10
so as to drive the motor
3
in response to an external motor operation command received on the interface circuit
12
. The power supply inverter
7
inputs the supply voltage magnitude, frequency, and phase, and voltage of the smoothing circuit
9
. When the smoothing circuit voltage becomes greater than the power supply voltage as in the regeneration mode, the power supply inverter
7
is driven at the same frequency and phase as the input power supply, thereby feeding back the energy to the input power supply
1
. Thus, the converter section
4
has a number of components, but a simple function, while the inverter section
5
has functions such as controlling the motor speed and rotation position and interfacing with an external controller and serves as the central function and fundamental operation of the motor operation controller
2
.
Next, the conventional examples for accommodating supply voltages incompatible with the voltage specifications of the motor
3
will be discussed. The following three methods can be used for accommodating supply voltages incompatible with the voltage specifications:
Method 1: The withstand voltage, allowable voltage, and current of the motor operation controller
2
and the motor
3
are considered for selecting components and designing the structure in response to input voltages.
Method 2: As shown in
FIG. 29
, the transformer
13
is inserted between the input power supply
1
a
and the motor operation controller
2
for making voltage conversion.
Method 3: As shown in
FIG. 31
, the internal DC voltage converter
20
is provided.
According to Method 1, 200VAC motor operation controllers and 200-VAC motors cannot be used at 400 VAC when considering the withstand voltage, and cannot be used at 100 VAC when considering the current capacity of main circuit parts because a double current is required, although the voltage becomes a half as compared with 200 VAC. As a result, the motor operation controllers
2
and the motors
3
of different types must be provided for various power supply voltages.
According to Method 2, different types of transformers must be provided for various voltages.
According to Method 3, the motor
3
having specifications different from the power supply voltage la can be used, but a transformer as in Method 2is required in order to provide insulation. Although a single internal inverter section can be used for various supply voltages, different types of motor operation controllers need to be provided.
FIG. 32
is a circuit diagram of an insulation type bidirectional DC voltage converter disclosed in U.S. Pat. No. 5,027,264, wherein numeral
21
is a primary smoothing circuit, numeral
22
is a secondary smoothing circuit, numeral
100
is an insulation type bidirectional DC voltage converter, numeral
110
is a switching element controller of the insulation type bidirectional DC voltage converter
100
, and numeral
120
is a voltage loop controller of the insulation type bidirectional DC voltage converter
100
. The insulation type bidirectional DC voltage converter
100
comprises primary switching elements
101
a
-
101
d
, an internal transformer
102
, a
Kaitani Toshiyuki
Kimata Masahiro
Kita Hirofumi
Ohnishi Yoshitaka
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
Vu Bao Q.
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