Claims:We claim:
1. An electromagnetic compliant motor controller (100) for high power permanent magnet ac motor (PMAC), comprising:
A power electromagnetic noise (EMI) filter (1) for filtering incoming AC supply from an external power source, and generating filtered AC;
A main power contractor (2) for ON/OFF control of input power;
a three-phase diode rectifier (5) for receiving the filtered AC, and generating rectified DC using a LC filter (6);
a three-phase IGBT inverter (7) for receiving the rectified DC, and generating AC voltage;
a digital signal processor based controller (11) for receiving the AC voltage, and driving a PMAC motor (12); and
a SMPS (10) to generate power supply for said digital signal processor based controller (11) by an EMI filter (8) and a single phase transformer (9).

2. The electromagnetic compliant motor controller (100) as claimed in claim 1, wherein said electromagnetic compliant motor controller (100) includes a precharge resistor (3) and a precharge contactor (4) connected in parallel to maintain a level of the rectified DC prior to start of the PMAC motor.

3. The electromagnetic compliant motor controller (100) as claimed in claim 1, wherein said electromagnetic compliant motor controller (100) includes an LC filter (6) coupled with said three-phase diode rectifier (5) for generating the rectified DC.

4. The electromagnetic compliant motor controller (100) as claimed in claim 1, wherein said three-phase IGBT inverter (7) is mounted on an aluminum heat sink for better cooling.
, Description:FIELD OF INVENTION:
[001] The present invention in general relates to motor control system. The present invention in particular relates to an electromagnetic compliant motor controller for high power permanent magnet ac motor (PMAC).
BACKGROUND AND PRIOR ART:
[002] Normally the control system of Permanent Magnet AC (PMAC) motor consists of switching power converter and control circuit for the power converter. The power converter usually has an inverter at its output stage which provides the required power to PMAC motor for its driving. The power converter contains high frequency switching device (e.g. IGBT) based power conversion system which are controlled precisely by fast operating digital signal processor (DSP) based control system.
Control system of Permanent Magnet AC (PMAC) motor mainly consists of power converters and controls for the power converters. The power converter usually has an inverter which provides the AC voltage for driving the motor. The power converter normally consists of IGBT based power conversion systems which are controlled precisely by fast operating digital signal processor based control systems.
[003] The control system for power converters mainly consists of fast digital signal processor (DSP) with its associated signal processing circuits, power switches, power filter and human interface for the system e.g. switches, push buttons, LED indicators etc. Electronic components with power converters are usually installed inside a control panel with internally mounted channels and supports for mounting the components. The electromagnetic emissions due to the switching components in the control panel of PMAC motor affects the functionality of the other control panels in the vicinity and vice-versa. The electromagnetic compatibility of the control panel of PMAC motor depends upon the design of the power circuit, construction of control panel and internal mounting arrangement of system components. Proper functioning of the motor control system also depends upon its compatibility against external electromagnetic emissions in its vicinity. In applications where the control system of Permanent Magnet AC (PMAC) motor has to work with external electromagnetically polluted environmental conditions, the design of metallic panel and inside mounting arrangements of the components play major role for proper operation of the system.

[004] Controllers for different power ratings of PMAC motor are available. The maximum power rating available for PMAC motor controller ranges from 10kW to 15kW. PMAC motor controller of higher power ratings of more than 40kW are not available as the high power PMAC motor applications are limited to specific areas. PMAC motors are being offered for special applications where high power rating machines of more than 40kW are required.

[005] PMAC motors with their controller are usually installed with other systems in the vicinity. Due to use of high frequency power switching devices (IGBTs) and switched mode power supplies (SMPS) along with the digital signal processor, which also operates at very high frequency (in MHz range), the electromagnetic emissions from the controller can be very high if it is not designed properly. These electromagnetic emissions have the ability to disrupt the operation of the other control systems installed in the vicinity. Vice-versa the motor controller operation can also get affected due to malfunction of sensitive electronic components with electromagnetic emissions originating from other control systems.
[006] Patent JP5121200B2 titled a permanent magnet electric motor control device relates to enhance system efficiency and to make compact furthermore by reducing loss of an inverter.
[007] Patent JP2010183784A titled controller for permanent magnet motor (en) is to provide a controller for a permanent magnet motor which prevents step-out of a sensorless drive permanent magnet motor and controls the magnet motor efficiently.
[008] Patent JP2004072909A titled controller for permanent-magnetic motor (en) is to remove signals unnecessary for rotor position detection and enhance the accuracy of position detection over a wide operating range in a controller for permanent magnet motor.
[009] The PMAC motor controller with high power rating of more than 40kW with electromagnetic compatibility as per MIL standards are not available.
[0010] Hence, the present invention provides an electromagnetic compliant controller for high power permanent magnet AC motor.
OBJECTS OF THE INVENTION:
[0011] The principal objective of the present invention is to provide an electromagnetic compliant controller.
[0012] Another object of the present subject matter is to provide an electromagnetic compliant controller for high power permanent magnet AC motor.
SUMMARY OF THE INVENTION:
[0013] The present invention aims to solve the problems mentioned above that exist with the available PMAC motor controllers. The PMAC motor controller consists of two stages of power conversion and a high speed digital signal processor based control system. The first stage of two stages power converter system consists of a three phase diode bridge rectifier for converting three phase line voltage to DC voltage. The second stage of power converter consists of an IGBT based three phase DC/AC inverter which converts the DC voltage to AC and drives the PMAC motor.
[0014] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0016] Fig. 1 illustrates Block Schematic of an electromagnetic compliant motor controller for high power permanent magnet ac motor (PMAC).
[0017] Fig. 2 illustrates Mounting arrangement of components in control panel.
[0018] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0019] The present invention will be described in detail below with reference to an embodiment as shown in the drawing.
[0020] Accordingly the present invention provides an electromagnetic compliant motor controller (100) for high power permanent magnet ac motor (PMAC).
[0021] Said electromagnetic compliant motor controller (100) for high power permanent magnet ac motor (PMAC) comprises of an electromagnetic noise filter (EMI) filter (1) for filtering the source noise entering in the system. The filtered AC supply is fed to the main power contactor (2) for ON/OFF control of input power. A precharge resistor (3) and a precharge contactor (4) are connected in parallel to maintain the DC voltage level prior to start of motor operation. A three phase diode rectifier (5) converts the incoming filtered AC voltage to DC voltage with a LC filter (6). A three phase IGBT inverter (7) generates AC voltage from the rectified DC voltage and drives a PM motor (12) with the help of a Digital Signal Processor Controller (11). A SMPS (10) generates power supply for said digital signal processor controller (11) with the help a EMI filter (8) and a single phase transformer (9).
[0022] All the components shown in figure-1 are housed in a special grade aluminum control panel with the help of mounting channels. The mounting arrangement of components inside the control panel are shown in figure-2. The components of said electromagnetic compliant motor controller (100) are mounted on the three sides on the inside walls of the control panel. Said components are mounted on the mounting plates and installed on the metallic channels inside the control panel. Said components of said electromagnetic compliant motor controller (100) are mounted in such a way that crisscross of power and control signal cables are minimum which ensures the minimum interference of signals and results in reduced electromagnetic emissions.
[0023] Further, the control panel is made of special grade aluminum material with conductive material coating on inside to arrest the electromagnetic radiations from the discreet electronic components.
[0024] Specially selected EMI gaskets (not shown) are installed on the all the edges of the control panel to arrest electromagnetic radiation. The EMI gaskets are selected on the basis of the operating frequency bands of the electronic components. The cooling vents of the control panels are designed to attenuate the radiations in the operating frequency range of electronic and switching components mounted inside of the panel. The cooling vents of control panel are also secured with conductive honey comb metallic meshes and EMI gaskets with high attenuation at the operating frequency band of components. The door of the control panel is secured with hybrid gasket for EMI and ingress protection (IP) to minimize the radiation with meeting of IP standards.
[0025] Figure.-2 shows the mounting of components inside the metallic panel. The IGBTs are mounted on the aluminum heat sink which are projected outside of the left wall of control panel for better cooling. The motor protection relay, over and under voltage relay and core balancing CT (CBCT) which are part of digital signal processor based controller (11), SMPS (10), Precharge resistor (3), precharge contactor (4) and power contactor (2) are mounted on the back wall of the control panel with mounting plates. Three phase diode rectifier (5), capacitors of LC filter (6) and three phase IGBT inverter (7) are mounted on left side walls to minimize the crisscross of power and signal cables. Electromagnetic noise filters (1) and (8) along with terminal block connectors are mounted on right wall of the control panel. Inductor of LC filter (6), single phase transformer (9) and SMPS (10) with terminal block connectors are mounted on the bottom plane of the control panel.
[0026] SYSTEM OPERATION
[0027] Initially said main power contactor (2) is in OFF state. Before turning ON said main power contactor (2), said LC filter (6) is charged through said precharge resistor (3) and said precharge contactor (4) circuit. After charging said LC filter (6), said precharge contactor (4) is turned OFF and said main power contactor (2) is turned ON. The DC voltage of said LC filter (6) is converted to AC voltage by said three phase IGBT inverter (7) which is fed to PMAC motor (12) terminals. Three phase source power supply is also fed to said EMI filter (8) and said single phase transformer (9) for generating single phase AC power source for SMPS (10) and said digital signal processor controller (11). Said digital signal processor controller (11) along with its auxiliary control circuits, generates the necessary control signals for said three phase IGBT inverter (7) to drive said PM motor (12).
[0028] Said power EMI filter (1) is used at the input stage of power circuit to prevent the electromagnetic noise entering into the system. Said electromagnetic compliant motor controller (100) has been tested for its electromagnetic compatibility as per MIL standards specifications mentioned in table-1.

TABLE-1
ELECTROMAGNETIC TESTS AND RESULTS AS PER MIL461E

Name of
Test Basic
Standard Description AC/ DC / Signal
Port/Enclosure
Observations

Conducted
Emissions
CE 101,
MIL STD 461 Conducted Emission on Power and interconnecting Leads (30 Hz to 10 kHz) 415V AC 3 phase input power cable
Within the limits

Conducted
Emissions
CE 102,
MIL STD 461 Conducted Emission on Power Leads and Inter connecting leads (10 KHz to 10 MHz)
415V AC 3 phase input power cable

Within the limits

Radiated
Emissions
RE 101,
MIL STD 461 Radiated Emission Magnetic Fields (30 Hz to 100 KHz)

Enclosure
Within the limits

Radiated
Emissions
RE 102
MIL STD 461 Radiated Emission Electric fields (10 kHz to 18 GHz)

Enclosure
Within the limits

Radiated
Susceptibility
RS 101
MIL STD 461 Radiated Susceptibility Magnetic fields (30 Hz to 100 kHz)

Enclosure
No Malfunction
Observed

Radiated
Susceptibility
RS 103
MIL STD 461 Radiated Susceptibility Magnetic fields (10kHz to 18GHz)

Enclosure
No Malfunction
Observed

Conducted
Susceptibility
CS 101
MIL STD 461 Conducted Susceptibility, Power Leads
30Hz to 150 kHz

Power Leads
No Malfunction
Observed

Conducted
Susceptibility
CS 114
MIL STD 461 Conducted Susceptibility Power & interconnecting Permanent leads 10kHz to 200 MHz

Power Leads
No Malfunction
Observed

Conducted
Susceptibility CS115
MIL-STD-461
Impulse Excitation.
415V AC 3-Phase
50Hz Input power cable

No malfunction was observed

[0029] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various assembly that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0030] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0031] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0032] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.