Device for quasi-sensorless control of high rotor pole switched reluctance motor

Abstract

The present disclosure provides an apparatus for quasi-sensorless control of high rotor pole switched reluctance motor. The apparatus includes: a switched reluctance motor (SRM) having a stator and a rotor; a three-phase inverter controlled by a processor connected to an input of the SRM; a load connected to the SRM via an inline torque meter; a converter connected to the load; and a software control module at the processor including: a rotor position estimation module utilizing a sequence of relationships between phase inductances of the HRSRM to determine an initial position of the rotor to estimate rotor position and establish a firm time base for the software control module; a time base module calculating shaft speed; a slope monitoring module monitoring a slope of a current waveform in an active phase; a pulse time module adjusting a pulse time based on the estimated time base; and a close control module fixing a close angle and establishing a current band for controlling the close angle to operate the SRM at a saturation level.

Description

[0001] This application is a divisional application of the invention patent application filed on April 8, 2018, with application number 201880003504.5 (international version PCT / US2018 / 026645) and entitled "Method and apparatus for quasi-sensorless adaptive control of switched reluctance motor driver".

[0002] Related applications

[0003] This application claims priority to U.S. Provisional Application No. 62 / 519807, filed June 14, 2017, the disclosure of which is incorporated herein by reference as if it were listed in its entirety. Technical Field

[0004] This invention generally relates to switched reluctance motor drive systems, and more specifically, to a system for rotor position estimation based on inductance measurements of the phase of a switched reluctance motor. Background Technology

[0005] A switched reluctance motor (“SRM”) is a rotating electric motor in which both the stator and rotor have salient poles. Due to their robust and sturdy construction, SRMs are viable candidates for a wide range of motor control applications. SRMs are driven by voltage strokes coupled to a given rotor position. An SRM is a brushless motor with multiple poles on both the rotor and stator. Unlike an unexcited rotor that has no stator, the stator has phase windings. Conversely, the rotor of an SRM is formed of a magnetically conductive material (typically iron) that attracts the magnetic flux generated by the windings on the stator poles when current flows through them. This magnetic attraction causes the rotor to rotate when the excitation to the stator phase windings is sequentially switched on and off according to the rotor position. For an SRM, a pair of radially opposed stator poles generate torque to attract a pair of corresponding rotor poles to align with the stator poles. As a result, this torque is generated in the movement of the SRM's rotor.

[0006] The use of switched reluctance motor (SRM) drives in industrial applications is a recent development. SRM drives have been considered a potential alternative to traditional drives in several variable speed drive applications. In traditional SRMs, a shaft position sensor, such as an encoder or resolver, generates a rotor position signal, which is then read by the controller. In an effort to improve reliability while reducing size and cost, various schemes have been proposed to eliminate the shaft position sensor by determining a reference commutation angle. These schemes implement indirect rotor position sensing by monitoring the motor's terminal voltage and current. The performance of a switched reluctance motor depends in part on the precise timing of phase energization relative to the rotor position. These methods are useful when at least one phase is energized and the rotor is rotating.

[0007] Another approach describes a system and method for sensorless control of an SRM drive using active phase voltage and current measurements. Sensorless systems and methods typically rely on a dynamic model of the SRM drive. Active phase currents are measured in real time, and these measurements are used to solve the dynamic equations representing the active phases using numerical techniques to obtain rotor position information. The phase inductance is represented by a Fourier series, with coefficients expressed as polynomial functions of the phase currents to compensate for magnetic saturation. The controller essentially operates an observer in parallel with the drive system. Since the motor's magnetic characteristics are accurately represented, the state variables calculated by the observer are expected to match the actual state variables. Therefore, the rotor position, also a state variable, will be indirectly available. This system teaches a general method for estimating rotor position using phase inductance measured from the active phases. Here, voltages are applied to the active phases, and the current response is measured to determine the position. This current amplitude is kept low to minimize any negative torque generated on the motor shaft.

[0008] Another approach describes a method for indirect motor position sensing involving applying a voltage-sensing pulse to an unexcited phase. The result is a change in phase current proportional to the instantaneous value of the phase inductance. The appropriate commutation time is determined by comparing the change in phase current with a reference current, thereby synchronizing the phase excitation with the rotor position. The phase excitation can be advanced or delayed by lowering or increasing the threshold, respectively. This commutation method utilizing the reactive phase of the SRM is limited to low speeds due to the unavailability of the inactive phase during higher speeds. Furthermore, although current and torque levels are relatively small in the reactive phase, they will contribute to the loss of SRM efficiency in such applications.

[0009] Another approach discloses a rotor position estimator for an SRM based on instantaneous phase flux and phase current measurements. Phase current and flux sensing is performed on phases in a predetermined sequence depending on the specific quadrant of the SRM operation. For each phase in the predetermined sensing sequence, phase flux and phase current measurements are performed during operation in a pair of predetermined sensing regions, each defined over a range of rotor positions. The rotor position estimate is obtained from the phase flux and phase current measurements for each corresponding phase during its corresponding sensing region. The rotor position estimate for each phase is normalized relative to a common reference phase, and the rotor position estimate for the SRM is calculated according to equations considering the fact that, for any given rotor position determined, the rotor poles of the SRM can be nearly aligned or misaligned. The sampled phase voltage and phase current are integrated to obtain the phase flux.

[0010] There remains a need for a quasi-sensorless adaptive control method for switched reluctance motor drives that utilizes a unique sequence of relationships between phase inductances to enhance the accuracy of rotor position estimation. This method monitors speed very closely with up to 30 updates per revolution, thus providing higher resolution than several currently used sensorless schemes. This desired method automatically adapts to variations in motor or process, as it does not assume complete consistency across all manufactured machines. Furthermore, this method will create a control algorithm that does not require calibration for all motor specifications and power ratings. Moreover, this method will be able to naturally calibrate the control algorithm to the inductance profile of the machine being tested. This system will not require any adjustments to the control algorithm and will also not require any prior knowledge of the motor's manufacturing specifications, further reducing the structural detail burden on machine manufacturers. The scheme will use its own set of steps for automatically calibrating the inductance profile of any machine, thus saving time and resources involved in machine setup and testing in industrial settings. Finally, the method is reliable, robust, fully scalable, and will provide a clear technique for actively seeking to calibrate the model to every machine manufactured. This embodiment overcomes the shortcomings in the art by achieving these key objectives. Summary of the Invention

[0011] In order to minimize the limitations found in existing systems and methods, and to minimize other limitations that will become apparent after reading this specification, preferred embodiments of the present invention provide a method and apparatus for quasi-sensorless adaptive control of high rotor pole switched reluctance motors (HRSRMs).

[0012] The method includes the following steps: The initial position of the HRSRM rotor is estimated using a unique sequence of relationships between the phase inductances of the HRSRM, and then the rotor is aligned relative to this initial position to start from a known phase and provide rotation in the correct direction. Current is applied to the active phase windings to rotate the motor, and the position is estimated using diagnostic pulses on the reactive phase windings during the initial rotation by estimating the inductance distribution. Voltage pulses are applied to the reactive phase windings, and the current response in each reactive phase is measured. Next, the system applies multiple diagnostic pulses to the reactive phases to identify the next phase and establishes a robust time base for the software control module on the magnetic sensor. The system then calculates the speed and updates the time base by generating motor index pulses from the magnetic sensor. The motor shaft speed is calibrated, which in turn calibrates the software encoder to operate on the time base. The method eliminates the switching threshold of the magnetic sensor and monitors the slope of the current waveform in the active phases to finely tune the firing angle from the encoder software. The pulse time t is based on the estimated time base and shaft speed. on It is adjusted to track any monitored speed changes. The dwell angle based on the axis speed is fixed.

[0013] A quasi-sensorless control device for a high-rotor-pole switched reluctance motor (HRSRM) includes: a switched reluctance motor having a stator and a rotor; a three-phase inverter controlled by a processor connected to the switched reluctance motor; a load; and a converter. The rotor includes multiple circumferentially spaced rotor poles and is rotatably associated with a motor shaft equipped with magnetic sensors. The three-phase inverter is adapted to act as a power supply for the switched reluctance motor, and the processor has a software control module and a software encoder. The load is connected to the switched reluctance motor via an inline torque meter, and the converter is connected to the load.

[0014] The first objective of this invention is to provide a quasi-sensorless adaptive control method for switched reluctance motor drives, which employs a unique sequence of relationships between phase inductances to enhance the accuracy of rotor position estimation.

[0015] A second objective of the present invention is to provide a method for monitoring and calculating shaft speeds and continuously updating them if any change in speed is detected.

[0016] A third objective of this invention is to provide a method for creating a control algorithm that requires calibration for all motor specifications and rated power.

[0017] A fourth objective of this invention is to provide a method for naturally calibrating a control algorithm to the inductance distribution of the machine being tested.

[0018] Another objective of the present invention is to provide a method and apparatus that do not require any adjustments to the control algorithm or any prior knowledge of the motor's manufacturing specifications, thus eliminating the need for structural details by the machine maker.

[0019] Another objective of this invention is to provide a method for automatically calibrating the inductance distribution of any machine, thereby saving time and resources for machine characterization and testing in industrial settings.

[0020] Another objective of this invention is to provide a reliable, robust, and scalable method that offers a clear technique for actively seeking to calibrate the model to each machine manufactured.

[0021] These and other advantages and features of the present invention have been specifically described so that those skilled in the art may understand the invention. Attached Figure Description

[0022] To enhance clarity and improve understanding of these various elements and embodiments of the invention, the elements in the drawings are not necessarily drawn to scale. Furthermore, to provide clear views of the various embodiments of the invention, elements not considered to be depicted are well-known and easily understood by those skilled in the art; therefore, for clarity and brevity, the drawings are simplified in form.

[0023] Figure 1 A flowchart of a method for controlling a high rotor pole switched reluctance motor (HRSRM) according to the present invention is shown;

[0024] Figure 2 This is a graph showing the inductance distribution according to the phase change of the three-phase SRM according to the present invention;

[0025] Figure 3 A block diagram of an apparatus for controlling a high rotor pole switched reluctance motor (HRSRM) according to the present invention is shown;

[0026] Figure 4A It is a graph showing the current waveform of a three-phase SRM under a specific load according to the present invention;

[0027] Figure 4B This is a graph showing the current waveform of a three-phase SRM under another load according to the present invention; and

[0028] Figure 4C This is a graph showing the current waveform of a three-phase SRM under another load according to the present invention. Detailed Implementation

[0029] In the following discussion of various embodiments and applications of the invention, reference is made to the accompanying drawings, which form part of this discussion and illustrate, by way of illustration, specific embodiments in which the invention can be practiced. It will be understood that other embodiments may be utilized and changes may be made without departing from the scope of the invention.

[0030] The following describes each inventive feature, which can be used independently of each other or in combination with other features. However, any single inventive feature may not solve any of the problems discussed above, or may only solve one of the problems discussed above. Furthermore, one or more of the problems discussed above may not be completely solved by any of the features described below.

[0031] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” include plural referents. Unless otherwise clearly stated, “and” and “or” are used interchangeably herein. As used herein, the term “about” means + / - 5% of the stated parameter. Unless the context clearly indicates otherwise, all embodiments of any aspect of the invention may be used in combination.

[0032] Unless the context explicitly requires otherwise, throughout the specification and claims, the words “comprise,” “comprising,” etc., shall be interpreted in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is, in the sense of “including but not limited to.” The use of singular or plural words shall also include both the plural and singular forms, respectively. Furthermore, when used in this application, the words “here,” “wherein,” “however,” “above,” and “below,” and words with similar meanings, shall refer to the entire application, not any particular part thereof.

[0033] The description of embodiments in this disclosure is not intended to be exhaustive or to limit the disclosure to the exact forms disclosed. While specific embodiments and examples of this disclosure have been described herein for illustrative purposes, various equivalent modifications are possible within the scope of this disclosure, as will be recognized by those skilled in the art.

[0034] Reference Figures 1 to 2 A flowchart of the method for controlling a high rotor pole switched reluctance motor (HRSRM) 100 according to the present invention is shown in Figure 1 As shown in the figure. The method 100 described in this embodiment enhances the accuracy of rotor position estimation and also allows at least one phase of the SRM to be positioned in a perfectly aligned position from rotation in a clockwise or counterclockwise direction. Method 100 allows for quasi-sensorless control of the speed in the switched reluctance motor and creates a control algorithm that is naturally calibrated with the inductance distribution of the SRM. For proper switching operation of the SRM, it is important to synchronize the stator phase excitation with the rotor position.

[0035] Method 100 includes the following steps: estimating the initial position of the rotor of the HRSRM using a unique sequence of relationships between the phase inductances of the HRSRM, as shown in block 102.

[0036] As the rotor rotates, each rotor pole becomes aligned with and misaligned with the stator poles, resulting in an inductance distribution in each stator pole. The inductance distribution of a three-phase SRM is as follows: Figure 2 As shown. For example, to estimate the initial rotor position, six starting regions are defined in the inductance distribution, such as... Figure 2 As shown, the values ​​of the phase inductance have a fixed relationship. Let L a L b and L c These are the inductances for phases A, B, and C, respectively. Based on the inductance relationship, it can be identified which phase(s) need to be energized to drive the motor to the perfectly aligned position. The initial position is determined by sequentially applying voltage pulses to each phase winding and measuring the time required for the phase current to reach a preset limit.

[0037] To determine the initial position, voltage pulses are applied sequentially to each phase winding, and the time required for the phase current to reach a preset limit is measured. The current rise time is a function of the phase inductance and the voltage pulse amplitude, given by the following equation:

[0038] E = L * di / dt

[0039] Where E is the applied voltage reference amplitude, L is the phase inductance, and i is the phase current.

[0040] The larger the inductance value, the longer it takes for the current to rise to the reference limit. For an initial phase current of zero and a reference current Iref, the time Tp to the reference is given below;

[0041] Tp = L * Iref / E

[0042] The initial position is identified by the measured current ramp-up time.

[0043] Based on the initial position, a hard alignment is established to start from a known phase and rotate in the correct direction, as shown in block 104. Current is applied to the active phase winding to rotate the motor, as shown in block 106. The active phase is essentially the phase with the rotor pole closest to the closest alignment position. During the initial rotation, the position is estimated by applying diagnostic pulses to the reactive phase winding and by estimating the inductance distribution, as shown in block 108. The inductance distribution of the SRM indicates that the inductance is maximum when the rotor is in the aligned position and minimum when the rotor is in the misaligned position. The next step is to apply voltage pulses to the reactive phase winding and measure the current response in each reactive phase, as shown in block 110. Multiple diagnostic pulses are applied to the reactive phases to identify when the next phase must be ignited, as shown in block 112, and to establish a robust time base for the software control module on the magnetic sensor, as shown in block 114. The magnetic sensor generates index pulses (20 edges per revolution) to calculate the speed and continuously update the time base. Multiple diagnostic pulses can be applied up to 10 rotations to establish a robust time base for the software control module to ignite the next phase. After 10 rotations, the software timing takes over, and the reactive phase is no longer needed to maintain operation. The motor speed is calculated and the time base is updated by generating motor index pulses from the magnetic sensor, as shown in block 116. Three signals are generated per rotor pole. In other words, for a motor with 10 rotor poles, the motor shaft speed is calibrated 30 times. This step is repeated 10 rotations (or more for greater accuracy) and is used to calibrate the software encoder to operate on this time base. As shown in block 118, the motor shaft speed is calibrated, and the software encoder is calibrated to operate on this time base. The time base is established to avoid any slippage in the calculated speed value. The method of the present invention also eliminates the switching threshold of the magnetic sensor, as shown in block 120. This ensures a robust time base is established in the control algorithm to avoid any slippage in the calculated value. The slope of the current waveform in the active phase is monitored to finely tune the ignition angle from the encoder software, as shown in block 122. The current slope is evaluated for a fixed duration to finely tune the ignition angle from the encoder software. The calculated shaft speed is updated 30 times per cycle to continuously track any changes in speed.

[0044] Based on the estimated time base, the pulse time t is adjusted individually for each phase. on As shown in block 124. This step adjusts the pulse t individually for each phase. on This is equivalent to 30 corrections per mechanical revolution. The method then monitors the shaft speed to track any changes in speed and fixes the closure angle based on the shaft speed, as shown in block 126. The speed can be monitored very closely, updating up to 30 times per revolution in this example, thus providing better resolution than several sensorless methods currently in use.

[0045] The closing angle is fixed based on speed. A current band is established; if the command current is lower than the lower band, the closing angle is reduced, and if the command current is higher than the higher band, the closing angle is increased. The closing angle decreases if the command current is lower than the lower band and increases if the command current is higher than the higher band. This has the effect of increasing the phase current at lower power levels, thus allowing the SRM to operate at higher saturation levels. For a given power output, reducing the closing angle will command a lower phase current.

[0046] Figure 3 A device 200 is described for quasi-sensorless control of a high-rotor-pole switched reluctance motor (HRSRM). The device 200 includes a switched reluctance motor 202 having a stator and a rotor. The rotor includes a plurality of circumferentially spaced rotor poles and is rotationally associated with a motor shaft having magnetic sensors. The HRSRM also includes a programmable brushless DC load 204 connected to the output of the switched reluctance motor 202 via an inline torque meter 206, and a converter 208 connected to the load. A software encoder is located in a control processor 210, which establishes a robust time base based on the magnetic sensors. As the rotor rotates, the rotor generates an inductance distribution in each stator pole as each rotor pole becomes aligned with and misaligned with the stator poles. Each rotor pole generates at least three signals to calibrate the motor shaft speed. A three-phase inverter 212, controlled by the control processor 210, is connected to the switched reluctance motor 202. The inverter 212 is adapted to serve as a power source for the switched reluctance motor 202, and the control processor 210 has a software control module and a software encoder.

[0047] The quasi-sensorless control of the high rotor pole switched reluctance motor (HRSRM) 202 naturally calibrates the control algorithm to the inductance distribution of the switched reluctance motor 202 under test. The switched reluctance motor 202 is scalable to all power levels, and the control algorithm does not necessarily need to be calibrated for all motor specifications and rated power. The switched reluctance motor 202 can automatically adapt to motor-to-motor or process variations.

[0048] In one embodiment, the system includes a method for controlling a high-rotor-pole switched reluctance motor (HRSRM), the method comprising the steps of: estimating the initial position of the HRSRM rotor using a unique sequence of relationships between the phase inductances of the HRSRM; applying current to the active phase windings to rotate the motor; applying voltage pulses to the reactive phase windings; measuring the current response in the reactive phase; applying multiple diagnostic pulses to the reactive phase to identify the next phase; establishing a robust time base for a software control module on the magnetic sensor; updating the time base by generating motor index pulses from the magnetic sensor; calculating the shaft speed of the motor and calibrating the software encoder to operate on that time base; canceling the switching threshold of the magnetic sensor; monitoring the slope of the current waveform in the active phase to finely tune the ignition angle from the encoder software; and adjusting the pulse time t based on the estimated time base. on Monitor shaft speed to track any changes in speed; and adjust the closure angle based on shaft speed and current.

[0049] refer to Figures 4A to 4C The current waveforms of a three-phase SRM under different loads according to the present invention are shown. The current waveforms of the three-phase SRM under a light load with a speed of 900 RPM and 1 Nm are shown. Figure 4A The current waveforms of a three-phase SRM under a partial load with a speed of 1200 RPM and 6 Nm are shown in the figure. Figure 4B middle. Figure 4C The current waveform of a three-phase SRM under full load with a speed of 1800 RPM and 6 Nm is shown. The method of the present invention monitors the slope of the current waveform to finely tune the ignition angle from the encoder software. Figures 4A to 4C The change in the closing angle according to load variations is shown. In response to current changes caused by load or command, a processor with a software control module advances or delays the timing of the current waveform. The advance or delay amount is selected to maintain the current slope at a constant reference value.

[0050] For purposes of illustration and description, the above description of preferred embodiments of the invention has been presented. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in accordance with the foregoing teachings. It is intended that the scope of the invention is not limited by this detailed description, but rather by the claims and their equivalents.

Claims

1. A device for quasi-sensorless control of a high rotor pole switched reluctance motor (HRSRM), comprising: A switched reluctance motor (SRM) has a stator and a rotor. A three-phase inverter, which is controlled by a processor connected to the input of the SRM; The load is connected to the SRM via an inline torque meter; A converter, which is connected to the load; and The software control module at the processor includes: The rotor position estimation module uses the sequence of relationships between the phase inductances of the HRSRM to determine the initial position of the rotor, in order to estimate the rotor position and establish a robust time base for the software control module. A time base module that calculates shaft speed and updates the time base by generating motor index pulses from a magnetic sensor of the motor shaft that is rotationally associated with the rotor; A slope monitoring module monitors the slope of the current waveform in the active phase to finely tune the ignition angle from the encoder software at the processor. A pulse timing module that adjusts the pulse time based on an updated time base; and A closure control module monitors the shaft speed and, based on the shaft speed, fixes the closure angle and establishes a current band for controlling the closure angle, thereby operating the SRM at a saturation level.

2. The apparatus according to claim 1, wherein, The three-phase inverter is adapted to supply power to the SRM.

3. The apparatus according to claim 1, wherein, The initial position of the rotor is determined by applying voltage pulses sequentially to each phase winding and measuring the time required for the phase current to reach a preset limit.

4. The apparatus according to claim 3, wherein, The applied voltage is given by the following: in, It is a phase inductance. It is the phase current, and It is the current rise time, which is a function of the phase inductance and the applied voltage.

5. The apparatus according to claim 1, wherein, The rotor position estimation module rotates the SRM by applying current to the active phase winding.

6. The apparatus according to claim 1, wherein, The rotor position estimation module estimates the rotor position by estimating the inductance distribution during the initial rotor rotation.

7. The apparatus according to claim 1, wherein, The rotor position estimation module is designed to apply voltage pulses to the reactive phase windings to measure the current response in each reactive phase, and to apply multiple diagnostic pulses to identify the next phase.

8. The apparatus according to claim 1, wherein, The time base module cancels the switching threshold of the magnetic sensor.

9. The apparatus according to claim 1, wherein, The time base is established to avoid offsets in the calculated velocity values.

10. A device for quasi-sensorless control of a high rotor pole switched reluctance motor (HRSRM), comprising: A switched reluctance motor (SRM) has a stator and a rotor. A three-phase inverter, which is controlled by a processor connected to the input of the SRM; The load is connected to the SRM via an inline torque meter; A converter, which is connected to the load; and The software control module at the processor includes: The rotor position estimation module uses a sequence of relationships between the phase inductances of the HRSRM to determine the initial position of the rotor. The position estimation module is designed to estimate the rotor position during the initial rotor rotation by estimating the inductance distribution, measuring the current response in each reactive phase, identifying the next phase, and establishing a robust time base for the software control module. A time base module that calculates shaft speed and updates the robust time base by generating motor index pulses from a magnetic sensor at the motor shaft; A slope monitoring module monitors the slope of the current waveform in the active phase to finely tune the ignition angle from the encoder software at the processor. A pulse timing module that adjusts the pulse time based on an updated time base; and A closure control module monitors the shaft speed to fix the closure angle based on the shaft speed and establishes a current band for controlling the closure angle, thereby operating the SRM at a saturation level.

11. The apparatus according to claim 10, wherein, The three-phase inverter is adapted to supply power to the SRM.

12. The apparatus according to claim 10, wherein, The position estimation module applies current to the active phase winding to rotate the SRM.

13. The apparatus according to claim 10, wherein, The position estimation module is designed to apply voltage pulses to the reactive phase winding to measure the current response in each reactive phase, and to apply multiple diagnostic pulses to identify the next phase.

14. The apparatus according to claim 10, wherein, The time base module updates the time base to cancel the switching threshold of the magnetic sensor.

15. A device for quasi-sensorless control of a high rotor pole switched reluctance motor (HRSRM), comprising: A switched reluctance motor (SRM) has a stator and a rotor. A three-phase inverter, controlled by a processor connected to the input of the SRM, is adapted to supply power to the SRM. The load is connected to the output of the SRM via an inline torque meter; A converter, which is connected to the load; and The software control module at the processor includes: The rotor position estimation module uses a sequence of relationships between the phase inductances of the HRSRM to determine the initial position of the rotor. The position estimation module is designed to estimate the rotor position by estimating the inductance distribution during the initial rotor rotation, apply voltage pulses to the reactive phase windings to measure the current response in each reactive phase, apply multiple diagnostic pulses to identify the next phase, and establish a robust time base for the software control module. The time base module calculates the shaft speed and updates the time base by generating motor index pulses from a magnetic sensor at the motor shaft, and cancels the switching threshold of the magnetic sensor. The slope monitoring module monitors the slope of the current waveform in the active phase to finely tune the ignition angle. A pulse timing module that adjusts the pulse time based on an updated time base; and A closure control module monitors the shaft speed and fixes the closure angle based on the shaft speed, and establishes a current band for controlling the closure angle, thereby operating the SRM at a saturation level.

16. The apparatus according to claim 15, wherein, The initial position of the rotor is determined by applying voltage pulses sequentially to each phase winding and measuring the time required for the phase current to reach a preset limit.

17. The apparatus according to claim 16, wherein, The applied voltage is given by the following: in, It is a phase inductance. It is the phase current, and It is the current rise time, which is a function of the phase inductance and the applied voltage.

18. The apparatus according to claim 15, wherein, The time base is established to avoid offsets in the calculated velocity values.

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