Description:DESCRIPTION
Technical Field
This disclosure relates generally to electric motor drives of a vehicle and more particularly to method and system for controlling active short circuit in electric motor drive of a vehicle.
BACKGROUND
Electric drive systems in electric vehicles utilize electric motor drives for efficiency and performance advantages. However, these systems face challenges in controlling the switching of Metal-Oxide-Semiconductor field-effect transistor (MOSFETs) during certain operating conditions, particularly during motor rotation such as coasting down or when the load generates reverse torque. One critical issue that arises is the dangerous buildup of Direct Current (DC) voltage in the system which poses a risk to the components connected to the DC bus system.
This problem is addressed by the implementation of an Active Short Circuit (ASC) to prevent damage to electric motor drive systems and associated elements caused by the dangerous buildup of DC voltage in the DC bus system. This buildup occurs due to back electromotive force (EMF) from the electric motor, particularly when there are failures to control the switching of MOSFETs, sensor failures, or overspeed conditions.
The activation of ASC is crucial to mitigate the risks associated with these conditions. However, the implementation of ASC brings its own set of challenges such as during extended ASC operations, short-circuited MOSFETs must handle substantial currents, leading to immense heat generation. Therefore, time for which ASC is activated needs to be controlled to avoid damage to the motor due to excessive heat buildup such as during towing of the vehicle and may necessitate a cooling system to prevent overheating and ensure continuous functionality. ASC activation also results in sudden braking of the vehicle, ranging from mild deceleration to regenerative braking or even panic braking, depending on the motor design and inverter MOSFET resistance. Sudden deceleration poses hazards for loads or vehicles, especially when unintended. Further, after coming to a stop due to ASC activation, the vehicle may experience difficulty in movement due to motor and inverter parameters resisting rotor motion. This could lead to the vehicle being stuck, causing operational issues and panic.
Accordingly, there is a requirement for a simple yet effective fail safe mechanism to ensure an effective control of activation of the ASC in electric motor drive of a vehicle.
SUMMARY OF THE INVENTION
In one embodiment, a method of controlling active short circuit (ASC) in an electric motor drive of a vehicle. The method may include comparing, by a comparator, a direct current (DC) bus voltage across the electric motor drive with respect to a pre-defined threshold voltage. The method may further include transmitting, by an ASC controller circuit to a microcontroller unit (MCU) an ASC activation signal based on the comparison by the comparator. The method may further include generating, by the ASC controller circuit, a pulse signal based on a pre-defined non-linear voltage function for a controlled active short circuit of the electric motor drive upon transmitting the ASC activation signal.
In another embodiment, a system of controlling active short circuit (ASC) in an electric motor drive of a vehicle is disclosed. The system may include a comparator that may be configured to compare a direct current (DC) bus voltage across the electric motor drive with respect to a pre-defined threshold voltage. The system may further include an ASC controller circuit configured to transmit an ASC activation signal by an ASC controller circuit to a microcontroller unit (MCU) based on the comparison by the comparator. The ASC controller circuit may be further configured to generate pulse signal based on a pre-defined non-linear voltage function for a controlled active short circuit of the electric motor drive upon transmitting the ASC activation signal.
It is to be understood that both the foregoing general description and the following detailed descriptions are exemplary and explanatory only and are not restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWING
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles.
FIG. 1 illustrates a system for enabling controlled active short circuit of an electric motor drive of a vehicle, in accordance with an embodiment of the present disclosure.
FIG. 2 illustrates a flowchart of a methodology of controlling active short circuit in electric motor drive of a vehicle, in accordance with an embodiment of the present disclosure.
FIG. 3 illustrates a detailed flowchart of methodology of controlling active short circuit in electric motor drive of a vehicle, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE DRAWINGS
The foregoing description has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which forms the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying other devices, systems, assemblies, and mechanisms for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristics of the disclosure, to its device or system, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
The terms “including”, “comprises”, “comprising”, “comprising of” or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a system or a device that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible, same numerals have been used to refer to the same or like parts. The following paragraphs describe the present disclosure with reference to FIGs. 1-3. As summarized above, in one broad aspect, the present invention provides a method and a system for controlling active short circuit in an electric motor drive of a vehicle. It is to be noted that the system may be employed in any vehicle including but is not limited to a passenger vehicle, a utility vehicle, a commercial vehicle, and any other transportable machinery. For the sake of clarity, vehicle is not shown.
FIG. 1 illustrates a system 100 for enabling controlled active short circuit of an electric motor drive 108 of a vehicle (not shown), in accordance with an embodiment of the present disclosure. In an embodiment, example of the electric motor drive 108 may include, but is not limited to, permanent magnet synchronous motors (PMSM). Such motors have high-power density and efficiency, but the use of permanent magnets may introduce a counter electromotive force (CEMF or back EMF), a voltage generated by the rotation of the motor (not shown). If motor (not shown) rotates at very high speed, the high back EMF induced can be dangerous in the event of a fault (e.g. failure of the control). The active short circuit (ASC) controller 102 may be configured to enable controlled active short circuit of an inverter 104 of the electric motor drive 108 in order to protect the DC power supply such as, but not limited to, a battery and other components of the vehicle in case of any failure in microcontroller unit (MCU) 110 or in case the motor induced back EMF is higher than DC bus voltage 106 across the electric motor drive 108. Scenarios in which active short circuit of the electric motor drive 108 may occur when the motor operates in the field weakening region at speeds higher than the base speed and the control of the motor by a motor control unit (not shown) is lost (due to an error). In another scenario, in case of a fault in the DC power supply due to problems in the battery such as inoperable fuse and the inverter 104 is unable to transfer energy from the battery, then energy stored in the motor is to be dissipated in order to prevent its failure. Further, it should be noted that uncontrolled enablement of active short circuit may generate braking effects and excessive heat. Accordingly, to prevent failure of the semiconductors used in the modules due to heat and other mechanical stress, there is a requirement to control active short circuit in a manner that no components are adversely affected due to heat generated, etc.
In order to achieve this, the system 100 includes an ASC controller circuit 102 electrically connected to an inverter 104.The ASC controller circuit 102 may be communicably and electrically connected to the MCU 110. In an embodiment, the MCU 110 may control the electric motor drive 108 by controlling various aspects of the inverter 104 such as, but not limited to, switching of the plurality of MOSFETs of the upper MOSFET bank 118 and the lower MOSFET bank 120 for handling high currents and voltages by switching them between conducting and non-conducting states.
Since active short circuit is a failsafe mechanism, it is required to be activated only in case of emergency. Thus, the MCU 110 may be configured to actively disable the ASC controller circuit 102 by transmitting a "disable ASC” signal to the ASC controller circuit 102 at all times. The system 100 includes a comparator 112 that may be used to compare the DC bus voltage 106 across the electric motor drive 108 with respect to a predefined threshold voltage. In an embodiment, the DC bus voltage 106 may be stepped down by step-down converter (not shown) to a safe operating limit of the comparator 112 before being input to the comparator 112. Further, the predefined threshold voltage may be predefined proportional to a level by which the DC bus voltage 106 may be stepped down before being input to the comparator 112 for an accurate comparison by the comparator 112.
The ASC controller circuit 102 may receive an input from the comparator 112 regarding the comparison of the DC bus voltage 106 across the electric motor drive 108 with respect to a predefined threshold voltage. Accordingly, the comparator 112 may output a signal to the ASC controller circuit 102 in case the DC bus voltage 106 across the electric motor drive 108 becomes greater than the predefined threshold voltage. Based on the signal received from the comparator 112 indicating that the DC bus voltage 106 across the electric motor drive 108 is greater than the predefined threshold voltage, the ASC controller circuit 102 may transmit an “ASC activation” signal to the MCU 110. The MCU 110, upon receiving the “ASC activation” signal from the ASC controller circuit 102 may override the active disablement of the ASC controller circuit 102 and stop the transmission of “disable ASC” signal to the ASC controller circuit 102. In one scenario, in case the MCU 110 has become faulty due to an error, the ASC controller circuit 102 may not receive the “disable ASC” signal from the MCU 110 and may lead to activation of the ASC controller circuit 102 in case the DC bus voltage 106 across the electric motor drive 108 is determined greater than the predefined threshold voltage.
Upon not receiving the “disable ASC” signal from the MCU 110, the ASC controller circuit 102 may be enabled to generate a pulse signal based on a predefined non-linear voltage function. The pulse signal may enable controlled active short circuit of the electric motor drive 108 upon receiving the “ASC activation” signal by the MCU 110 and based on the comparison of the comparator 112.
It is to be noted that the inverter 104 may convert Direct Current (DC) from a DC power supply 106 into an alternating current (AC) to power the electric motor drive 108. The inverter 104 may include an upper Metal-Oxide-Semiconductor-field transistor (MOSFET) bank 118, and a lower MOSFET bank 120 arranged in a configuration known as an inverter bridge.
In an embodiment, the ASC control circuit 102 may be powered by an emergency DC power supply 116 that may draw power from DC bus voltage 106 that may act as an independent emergency power supply. In an embodiment, the power drawn from the DC bus voltage 106 may be regulated to bring it in safe operating limits of the comparator 112 and the ASC control circuit 102 by a voltage regulator 115. The voltage regulator 115 may regulate the voltage level from the DC bus voltage 106 to a predefined voltage level sufficient to power the comparator 112 and the ASC control circuit 102. The pulse signal generated by the ASC controller circuit 102 may be supplied to either the upper MOSFET bank 118 or the lower MOSFET bank 120. It is to be noted that the pulse generated based on the pre-defined non-linear voltage function may be based on a plurality of parameters comprising open circuit voltage, braking torque and heating effect corresponding to the electric motor drive 108. As mentioned above, semiconductors and other modules may have a tolerance level for the current it can withstand, and heat generated due to active short circuit. Further, it may be desired to generate safe level of braking torque depending on the speed of the vehicle or the type of motor to ensure safety of the vehicle during active short circuit. Accordingly, the pre-defined non-linear voltage function may be based on formula given by equation (1) given below:
g[min{f\left(braking\ torque)+f\left(OCV\right)+f\left(heating\ effect\right)\right\}] ………….. (1)
Thus, the pulse signal generated by the ASC controller circuit 102 based on the pre-defined non-linear voltage function of equation (1) may ensure controlled active short circuit by firing either the upper MOSFET bank 118 or the lower MOSFET bank 120. In an embodiment, the pulse signal may have a predefined frequency and predefined amplitude based on the pre-defined non-linear voltage function. Further, the pulse signal may be used to the fire either the upper MOSFET bank 118 or the lower MOSFET bank 120 for a pre-defined time. In case of firing of the lower MOSFET bank 120 for the pre-defined time and the DC bus voltage 106 across the electric motor drive 108 is not determined less than the predefined threshold voltage level, the upper MOSFET bank 118 may be subsequently fired for the predefined time until the DC bus voltage 106 across the electric motor drive 108 becomes less than the predefined threshold voltage level. Similarly, in case of firing of the upper MOSFET bank 118 initially, if the DC bus voltage 106 across the electric motor drive 108 is not determined less than the predefined threshold voltage level, the lower MOSFET bank 120 may be subsequently fired for the predefined time until the DC bus voltage 106 across the electric motor drive 108 becomes less than the predefined threshold voltage level.
The conventional active short-circuit is enabled by switching ON the MOSFETs of the upper MOSFET bank 118 and subsequently keeping the MOSFETs of the lower MOSFET bank 120 switched OFF or vice versa. The MOSFETs of the upper MOSFET bank 118 or the lower MOSFET bank 120 when switched ON may create a low-resistance path for the motor current, which may cause a rapid increase in current flow through circuit of the inverter 104, leading to the dissipation of electrical energy as heat. The energy dissipation rate may depend on factors such as magnitude of the current and resistance of short-circuit path in the inverter 104.
Thus, controlled active short circuit is crucial to mitigate the risks associated with the excessive voltage buildup. Further, controlled active-short circuit based on the pulse signal generated by the ASC control circuit 102 may help to avoid damage to the electric motor drive 108 due to excessive heat buildup, open circuit voltage, etc. Further, the controlled active short-circuiting may also control braking of the vehicle, thus avoids sudden deceleration of the vehicles that may pose hazards for loads or vehicles, especially when unintended. Further, as a result of controlled ASC, the electric motor drive 108 may not require a reset and the vehicle may be towed easily if required.
Thus, the ASC control circuit 102 of the present disclosure addresses various challenges associated with uncontrolled active short circuit of by enabling precise activation and deactivation of active short circuit based on a voltage thresholds and the predefined non-linear function. Further, the ASC control circuit 102 may again be actively disabled by the MCU 110 in case the comparator 112 determines that the DC input voltage is below the predefined threshold voltage. Further, in case the MCU 110 determines that the system is safe to operate based on its intelligent monitoring and supervision of failures (sensors failures involving position, voltage, current, temperature sensors and failure of other components / functions) including the condition that the DC bus voltage 106 is below the predefined threshold voltage, the MCU 110 may actively disable the ASC controller circuit 102.
Referring now to FIG. 2, a flowchart 200 of a methodology of controlling active short circuit in electric motor drive 108 of a vehicle is illustrated, in accordance with an embodiment of the present disclosure. The flowchart 200 may include a plurality of steps. It is to be noted that FIG. 2 is explained in conjunction with FIG. 1.
At step 202, the comparator 112 may compare the DC bus voltage 106 across the electric motor drive 108 with a pre-defined threshold voltage. In an embodiment, MCU 110 of the vehicle (not shown) may be configured to actively disable the ASC controller circuit 102 by transmitting a “disable ASC” signal. In an embodiment, the MCU 110 may be configured to actively disable the ASC controller circuit 102 if the DC bus voltage 106 across the electric motor drive 108 may be determined less than the pre-defined threshold voltage.
Further at step 204, the ASC controller circuit 102 may transmit an “ASC activation” signal to the MCU 110 based on the comparison by the comparator 112 at step 202. In an embodiment, the “ASC activation” signal may be transmitted by the ASC controller circuit 102 until the DC bus voltage 106 across the electric motor drive 108 may be determined greater than the pre-defined threshold voltage.
Further, at step 206, upon transmitting the “ASC activation” signal, the ASC controller circuit 102 may generate a pulse signal based on a pre-defined non-linear voltage function as mentioned above in equation (1), for a controlled active short circuit of the electric motor drive 108. In an embodiment, the pre-defined non-linear voltage function of equation (1) may be based on a plurality of parameters including open circuit voltage, braking torque, and heating effect corresponding to the electric motor drive 108. The controlled active short circuit of the electric motor drive 108 may be enabled by firing the lower MOSFET bank 120 or the upper MOSFET bank 118 based on the pulse signal for a pre-defined time.
In an embodiment, subsequent to the firing of the lower MOSFET bank 120 in case the DC bus voltage 106 across the electric motor drive 108 may be determined greater than the pre-defined threshold voltage after the pre-defined time, the upper MOSFET bank 118 may be fired based on the pulse signal. In another embodiment, in case the upper MOSFET bank 118 is fired for a predefined time and in case the DC bus voltage 106 is determined greater than the pre-defined threshold voltage, the lower MOSFET bank 120 may be fired subsequently based on the pulse signal.
Referring now to FIG. 3, a detailed flowchart 300 of a methodology of controlling active short circuit in electric motor drive 108 of a vehicle is illustrated, in accordance with an embodiment of the present disclosure. The flowchart 300 may include a plurality of steps and is explained in conjunction with FIGs. 1 and 2.
At step 302, the MCU 110 may actively disable the ASC controller circuit 102 by transmitting a “disable ASC” signal to the ASC controller circuit 102. Further at step 304, the DC bus voltage 106 across the electric motor drive 108 may be compared with respect to a predefined threshold using the comparator 112. In case the DC bus voltage 106 across the electric motor drive 108 is determined less than the pre-defined threshold voltage, the MCU 110 may continue to actively disable the ASC controller circuit 102 at step 302.
Further, in case the DC bus voltage 106 across the electric motor drive 108 is determined greater than the pre-defined threshold voltage at step 304, the ASC controller circuit 102 may transmit an “ASC activation” signal to the MCU 110 at step 306. In an embodiment, the “ASC activation” signal may be transmitted by the ASC controller circuit 102 until the DC bus voltage 106 across the electric motor drive 108 may be determined greater than the pre-defined threshold voltage.
Further at step 308, upon transmitting the “ASC activation” signal, the ASC controller circuit 102 may generate a pulse signal based on a pre-defined non-linear voltage function (as given in equation (1) above) for firing the lower MOSFET bank 120 based on the pulse signal for a pre-defined time. In an embodiment, the pre-defined non-linear voltage function may be based on a plurality of parameters including open voltage circuit, braking torque, and heating effect corresponding to the electric motor drive 108.
Further, at step 310, after firing the lower MOSFET bank 120 for a pre-defined time, the DC bus voltage 106 may be compared with respect to the pre-defined threshold voltage using the comparator 112. In case, subsequent to firing the lower MOSFET bank 120 for pre-defined time, the MCU 110 may actively disable the ASC controller circuit 102 at step 302. Further, subsequent to firing the lower MOSFET bank 120, in case the DC bus voltage 106 is still determined greater than the pre-defined threshold voltage at step 310, the ASC controller circuit 102 may transmit the pulse signal to fire the upper MOSFET bank 118 at step 312. In an embodiment, the DC bus voltage 106 across the electric motor drive 108 may not reduce upon firing the lower MOSFET bank 120 due to failure of the MOSFETs of the lower MOSFET bank 120. In an embodiment, a MOSFET failure may occur in either of the upper MOSFET bank 118 and the lower MOSFET bank 120. Thus, the comparison of the DC bus voltage 106 with respect to the predefined threshold after initial firing of the upper MOSFET bank 118 or lower MOSFET bank 120 may ensure that the DC bus voltage 106 becomes below the predefined threshold voltage effectively. Further at step 314, the ASC control circuit 102 may be disabled, and a system reset may be awaited.
Thus, the disclosed method and system provides a simple and effective failsafe mechanism of controlling active short circuit and overcomes the technical problem of the existing active short circuit systems. The incorporation of the ASC controller circuit 102, allows to effectively control active short circuit and preventing any damage to the DC power supply and the activation and deactivation of the active short circuit of the electric motor drive 108 of a vehicle overcoming the existing side effects related to excessive heating, breaking and high open circuit current.
As will be appreciated by those skilled in the art, the design described in the various embodiments discussed above are not routine, or conventional, or well-understood in the art. The techniques discussed above provide the integration of ASC controller circuit 102. In light of the above-mentioned advantages and the technical advancements provided by the disclosed method and system, the claimed steps as discussed above are not routine, conventional, or well understood in the art, as the claimed steps enable the following solutions to the existing problems in conventional technologies. Further, the claimed steps bring an improvement in the functioning of the device itself as the claimed steps provide a technical solution to a technical problem.
The specification has described method and system for controlling active short circuit in electric motor drive 108 of a vehicle. The illustrated steps are set out to explain the exemplary embodiments shown, and it should be anticipated that ongoing technological development will change the manner in which particular functions are performed. These examples are presented herein for purpose of illustration, and not limitation. Further, the boundaries of the functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternative boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. Alternatives (including equivalents, extensions, variations, deviations, etc., of those described herein) will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. Such alternatives fall within the scope and spirit of the disclosed embodiments.
It is intended that the disclosure and examples be considered as exemplary only, with a true scope of disclosed embodiments being indicated by the following claims.

, Claims:I/We Claim
1. A method (200) of controlling active short circuit (ASC) in an electric motor drive (108) of a vehicle, comprising:
comparing (202), by a comparator (112), a direct current (DC) bus voltage (106) across the electric motor drive (108) with a pre-defined threshold voltage;
transmitting (204), by an ASC controller circuit (102) to a Microcontroller unit (MCU) (110), an ASC activation signal based on the comparison by the comparator (112); and
generating (206), by the ASC controller circuit (102), a pulse signal based on a pre-defined non-linear voltage function for a controlled active short circuit of the electric motor drive (108) upon transmitting the ASC activation signal.

2. The method (200) as claimed in claim 1, wherein the MCU (110) is configured to actively disable the ASC controller circuit (102),
wherein the ASC activation signal is transmitted by the ASC controller circuit (102) to override the active disablement of the ASC controller circuit (102) until the DC bus voltage (106) across the electric motor drive (108) is determined greater than the pre-defined threshold voltage.

3. The method (200) as claimed in claim 2, wherein the MCU (110) is configured to actively disable the ASC controller circuit (102) if DC bus voltage (106) across the electric motor drive (108) is determined less than the pre-defined threshold voltage.

4. The method (200) as claimed in claim 1, wherein the pre-defined non-linear voltage function is based on a plurality of parameters comprising open circuit voltage, braking torque and heating effect corresponding to the electric motor drive (108).

5. The method (200) as claimed in claim 1, wherein the electric motor drive (108) comprises a lower MOSFET bank (120) and an upper MOSFET bank (118), wherein the controlled active short circuit of the electric motor drive (108) is enabled by firing the lower MOSFET bank (120) or the upper MOSFET bank (118) based on the pulse signal for a pre-defined time.

6. The method (200) as claimed in claim 5, wherein subsequent to the firing of the lower MOSFET bank (120), in case the DC bus voltage (106) across the electric motor drive (108) is determined greater than the pre-defined threshold voltage after the pre-defined time, the upper MOSFET bank (118) is fired based on the pulse signal.

7. The method (200) as claimed in claim 5, wherein subsequent to the firing of the upper MOSFET bank (118), in case the DC bus voltage (106) across the electric motor drive (108) is determined greater than the pre-defined threshold voltage after the pre-defined time, the lower MOSFET bank (120) is fired based on the pulse signal.

8. The method (200) as claimed in claim 1, wherein the comparator (112) and the ASC controller circuit (102) are powered based on a stepped down DC bus voltage (106).

9. A system (100) of controlling active short circuit (ASC) in an electric motor drive (108) of a vehicle, comprising:
a comparator (112) configured to compare a direct current (DC) bus voltage (106) across the electric motor drive (108) with respect to a pre-defined threshold voltage; and
an ASC controller circuit (102) configured to:
transmit an ASC activation signal by the ASC controller circuit (102) to a (microcontroller unit) (MCU) (110) based on the comparison by the comparator (112); and
generate a pulse signal based on a pre-defined non-linear voltage function for a controlled active short circuit of the electric motor drive (108) upon transmitting the ASC activation signal.

10. The system (100) as claimed in claim 9, wherein the MCU (110) is configured to actively disable the ASC controller circuit (102), and
wherein the ASC activation signal is generated by the ASC controller circuit (102) to override the active disablement of the ASC controller circuit (102) until the DC bus voltage (106) across the electric motor drive (108) is determined greater than the pre-defined threshold voltage.

11. The system (100) as claimed in claim 10, wherein subsequent to the transmission of the ASC activation signal, the MCU (110) is configured to actively disable the ASC controller circuit (102) if DC bus voltage (106) across the electric motor drive (108) is determined less than the pre-defined threshold voltage.

12. The system (100) as claimed in claim 9, wherein the pre-defined non-linear voltage function is based on a plurality of parameters comprising open circuit voltage, braking torque and heating effect corresponding to the electric motor drive (108).

13. The system (100) as claimed in claim 9, wherein the electric motor drive (108) comprises a lower MOSFET bank (120) and an upper MOSFET bank (118), wherein the controlled active short circuit of the electric motor drive (108) is enabled by firing the lower MOSFET bank (120) or the upper MOSFET bank (118) based on the pulse signal for a pre-defined time.

14. The system (100) as claimed in claim 13, wherein subsequent to firing of the lower MOSFET bank (120), in case the DC bus voltage (106) across the electric motor drive (108) is determined greater than the pre-defined threshold voltage after the pre-defined time, the upper MOSFET bank (118) is fired based on the pulse signal.

15. The system (100) as claimed in claim 13, wherein subsequent to the firing of the upper MOSFET bank (118), in case the DC bus voltage (106) across the electric motor drive (108) is determined greater than the pre-defined threshold voltage after the pre-defined time, the lower MOSFET bank (120) is fired based on the pulse signal.

16. The system (100) as claimed in claim 9, wherein the comparator (112) and the ASC controller circuit (102) are powered based on a stepped down DC bus voltage (106).