JPH0993985A - Method and device that control electric current profile in srm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise of SRM by outputting a PWM signal to at least one of two switches in response to an input from a PWM signal generator or a microprocessor thereby controlling the current to winding. SOLUTION: A circuit 10 comprises a PWM signal generator 16 for providing an operation signal to one or both of switches S1, S2 and both the PWM signal generator 16 or a microprocessor generates a PWM signal of 'soft' chopping signal or 'hard' chopping signal. When the current profile is controlled at the energizing part of each phase so that the noise of a motor is reduced, the current level is increased at first to a peak level higher than a normal level and then it is lowered to the normal level when the phase is deenergized. Since the inclination of current profile becomes gentler when the phase is deenergized as compared with other case, noise of SRM can be lowered.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to switched reaction motors (abbreviated herein as "SRM"), and more particularly to controlling or operating a current profile for an electric motor. The present invention relates to a method and device for reducing noise of an electric motor.

[0002]

Switched reaction motors, or SRMs, are well known in the art. One problem with operating this type of electric motor is noise. Such noise is one source of this noise in the phase windings of the motor as each phase is switched at the end of the cycle, as described in US patent application Ser. No. 175,268 by the inventor of the present application. It is caused by the dissipation of the current. When the motor is switched from one phase to another, about 3 of the energy supplied to the phase winding while the phase winding is energized.
About 0% of energy is attenuated. A portion of this energy is recovered or dissipated using a storage capacitor, as described in the above-referenced US patent application.

Generally, the main causes of noise of an electric motor are
That is, the vertical force acting between the stator and rotor of the electric motor changes abruptly. Also, noise is particularly severe when such abrupt changes occur at the point of maximum deformation of the motor cycle. US Pat. No. 5,239,217 filed by the inventor of the present application describes a phenomenon called “elliptical deformation”. This phenomenon is a condition in which the substantially circular rotor and stator of the electric motor are deformed into an elliptical shape by the force generated when the rotor and stator poles are aligned with each other. The above-mentioned US patent applications and patents describe methods for reducing such elliptical deformation forces.

While the methods described in the above-referenced US patent applications and patents are effective in reducing motor noise, other methods of further reducing motor noise are also important. One such method is to control the current profile of each phase of the motor. In one control method in which the current is controlled to reduce torque, various look-up tables and schedules are used to achieve control (see US Pat. No. 4,868,477). It is also known to control the current profile by increasing the phase length and thus the phase dwell time (US Pat. No. 4,253,0).
53). The third method is "Performance Enhancemen".
t of Single-phase Switched Reluctance Motor by DC
S. Chan and HR entitled "Link Voltage Boosting"
Paper by Bolton (IEEE Proceedings-B, Volume 140,
Paper No. 5, September 1993). In this paper, current is supplied to the phase, and then the current is removed faster than normal by using a boost voltage at the beginning of the end of the phase. One drawback of this method is its lack of flexibility.

Although the above-mentioned methods are effective, a large amount of circuits and a large amount of operations are required to achieve sufficient control in these methods. Other methods of controlling the current profile are even more effective and easily achievable. Noise reduction is achieved by matching the slope of the current profile at the end of the energized portion of the phase with the slope of the tail current damping portion of the current profile as closely as possible. The present inventor has proposed an apparatus and method for controlling tail current decay in the above-mentioned U.S. Patent Application No. 175,268. According to this method, the slope of the decaying part of the current profile can be controlled. In contrast, the circuit and method of the present invention achieve a smooth change in the current profile without affecting the energizing zones of the phase or other important operating parameters of the motor, thereby significantly reducing noise. Thus, the phase biasing portion of the current profile can be controlled.

[0006]

SUMMARY OF THE INVENTION Some of the objects of the present invention are single-phase or two-phase SRMs, for example two-phase and three-phase SRMs such as 12-6 type two-phase SRMs and 6-4 type three-phase SRMs. Providing a control method and apparatus for operating a current profile in each phase, providing a control method and apparatus for controlling a current profile in an energized portion of each phase to reduce noise of a motor, and hard chopping Or, to provide a control method and a device for controlling a current profile by using a current control method by soft chopping, to provide a control method and a device for increasing a current level to a peak value higher than a normal current level, In the normal energized portion of the phase, the current profile is reduced when the current is reduced below its peak value to a level below the peak value, which causes the phase to deactivate. Providing a control method and apparatus in which the change in slope of the tool is much more gradual than in other cases, can be easily incorporated into existing SRM control circuitry, and may include a microprocessor. To provide a control method and device, and to provide a control method and device for increasing the current to a peak value by increasing the voltage applied to the phase winding at first.
It controls the duty cycle of the PWM signal used to control the current flowing in the phase windings when the phase becomes energized, which causes the current to rise rapidly to its peak value at the beginning of the phase energization interval. Providing a control method and device for controlling, and a control method and device for controlling the frequency of the PWM signal to achieve the same result.
Providing a control method and apparatus for varying both the duty cycle and frequency of a PWM signal to achieve the same result, acting on the motor when the phase of the motor changes from an energized state to a de-energized state. PROBLEM TO BE SOLVED: To provide a control method and apparatus for correcting a vertical force generated in a motor so that a leveled elliptical deformation force changes gently, thereby reducing ringing in the motor, SRM
It is an object of the present invention to provide an inexpensive and highly reliable control circuit that reduces noise over the entire operating range.

In accordance with the present invention, generally stated, there is provided an apparatus for controlling the current profile in the energized portion of the phase of a single-phase or multi-phase SRM. The switch is closed to conduct current to the winding when the phase is in the energized state. Hall effect sensors and other types of sensors are used to detect various operating parameters of the SRM. A PWM signal generator or microprocessor having a PWM signal output terminal responds to the input from the sensor and outputs a PWM operation signal to at least one of the two switches to control the current to the winding. The actuation signal controls the switch such that the behavior of the switch is controlled as a function of the signal characteristics of the actuation signal. As a result, the supply of current to the windings follows a predetermined profile. According to this predetermined profile, the current is initially rapidly increased from zero to a peak value when the phase is energized. The current is then reduced to a second value below the peak value by the time the phase is de-energized. Further, the current drops below the second value to 0 when the phase is de-energized. The change in the current profile that occurs when the phase switches from the energized state to the de-energized state is a gentle rather than abrupt change. This gradual change reduces the degree of ringing that typically occurs in the motor when the supply of current to the winding is stopped, thereby reducing the noise of the motor. Also disclosed herein is a method of controlling a current profile.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention;

In the accompanying drawings, the switching reaction motor M (see FIGS. 6A and 6B) is a single-phase switching reaction motor or a two-phase, three-phase or four-phase motor. Well, typically a polyphase motor. Examples of such an electric motor are a 12-6 type two-phase electric motor and a 6-4 type three-phase electric motor. The electric motor has a stator assembly S including a plurality of stator teeth ST (only one of which is shown in the drawing). The electric motor further includes a rotor assembly R mounted on the shaft H and arranged to rotate relative to the stator assembly, the rotor assembly R having a plurality of rotor teeth RT. When the rotor rotates in the clockwise direction as shown, a force is generated on the stator assembly and the rotor assembly. These forces have a maximum value when the rotor teeth directly face the stator teeth, as shown by the lengths of the arrows in FIGS. 6 (A) and 6 (B), respectively. These forces produce an elliptical deformation effect on the motor.

During operation of the motor, each phase of each motor is sequentially energized and de-energized. The time that each phase is energized depends on various operating parameters, and various control methods have been developed in the prior art to determine when the switch from one phase to the next should occur. When the phases are energized, current is supplied to the phase winding W of the motor. Current is continuously supplied to the windings while the phases are energized. As shown in FIG. 4B, the supply of current to the winding starts at time To.

The device 10 of the present invention is used to control the current profile P (see FIG. 4D) in a single-phase or multi-phase switched reaction motor M during the energizing portion of each phase. . As shown in FIG. 1, the phase winding W is connected to the DC bus by the switch device 12. The switch device is adapted to conduct current to the winding when the phases are energized, connecting a first switch S1 connecting the winding to one side of the bus and a winding to the other side of the bus. And a second switch S2 for switching. The switch device also includes corresponding diodes D1 and D2, respectively. When the phase represented by the winding is in the energized state, switches S1 and S2 are closed.

Various detection devices are provided for detecting the operating parameters of the electric motor. For example, in FIG. 6A, a Hall effect sensor 14 for detecting the instantaneous position of the rotor assembly R is provided. Although not shown in the figure, other sensors for outputting the rotational speed and torque of the electric motor and parameter information similar to these are also provided. Further provided is a signal generator, generally designated 16 in FIG. 1, which includes a PWM signal generator which controls the current to the winding W. Therefore, an operation signal is output to one or both of the switches S1 and S2 for the reason described below. Also shown in FIG. 1 is a controller, generally indicated at 18, which controls the operation of the signal generator in response to an input signal from the detector. The control device controls the operation of the signal generator such that the signal generator outputs an operation signal having an operation characteristic that causes the current to be supplied to the winding according to a predetermined profile.

In FIGS. 4A, 4B and 5A, a typical current profile P1 for one phase of the motor and the leveled force generated in the motor are illustrated. There is. In particular, in FIG. 4B, the current level is shown to be zero before the particular phase corresponding to the winding is energized. The phase becomes energized at time To. Then, the current is supplied to the phase winding until the time Tc. At time Tc, the phase is de-energized,
No current is supplied to the winding. From time Tc to time Tf
By then, the current gradually decreases to zero. As the current begins to flow through the phase windings, the current level rises to level Ip and reaches this level at time Tx. From time Tx to time Tc, the current flowing through the winding is constant,
Maintained at level Ip. When the supply of current to the winding is stopped at time Tc, the slope of the current profile changes abruptly. This is due to the fact that the current in the winding is sharply reduced to less than Ip at time Tc as indicated by the steep slope of the current profile. The inductance profile L for winding W is shown in FIG. 4A, showing the inductance in the winding for the current delivered to the phase according to the profile of FIG. 4B. As shown in FIG. 5 (A),
The leveled force profile F1 for the motor also shows a sharp change at the time Tc when the current is cut off. Thus, the slope of the leveled force profile changes abruptly, resulting in a waveform V1 in FIG. 5 (A).
The noise ringing indicated by is generated. This ringing produces a high level of noise in the motor, which is undesirably high.

Generating a current profile, such as profile P2 shown in FIG. 4D, is a circuit 1 of the present invention.
0 and one feature of the method. According to the method of the present invention, the current into the winding rises sharply from zero to a peak value Ip 'when the phase is energized. As shown in FIG. 4D, the current is raised to this peak value between the time points To and Tx. At time Tx, the current begins to decrease and the current is at a second value below the peak value, for example current level I, until the phase is de-energized at time Tc.
It is reduced to p. The current then decreases to zero from this second value when the phase is de-energized. Thus, the advantage of controlling the current profile is that time Tx and time Tc
That is, the slope of the current profile between and does not become substantially horizontal as occurs in the typical situation of FIG. That is, the current profile has a negative slope that is similar to the slope from time Tc to time Tf and has a small slope. Therefore, even if the supply of current to the phase is stopped at time Tc, the change in the current profile that occurs is not a sudden change but a much gentler and smoother change. In FIG. 5B, which shows the leveled force profile F2 of the motor in the case where current is supplied to the phases according to profile P2, the current state of the motor is when the current to the winding is stopped. The degree of ringing occurring in the above is reduced by the above-mentioned gentle and smooth change. This is shown by the waveform V2 in FIG. 5B, and the noise of the electric motor is greatly reduced as shown.

As described above, the circuit 10 of the present invention includes the switch S.
PWM to supply operating signal to one or both of 1 and S2
A signal generator 16 is included. Alternatively, as shown in FIG. 2, circuit 10 'provides P to provide the operating signal to the switch.
It includes a microprocessor having a WM signal output terminal. Both the signal generator 16 and the microprocessor 20 can output a PWM signal that is a "soft" chopping signal or a "hard" chopping signal.
The PWM signal for soft chopping is shown in FIG. 3A, and the PWM signal for hard chopping is shown in FIG. 3B. If the signal generator or microprocessor outputs a soft chopping signal, that signal is only fed to one switch, for example switch S2, which causes the switch to move between the "on" and "off" positions. Can be switched. The other switch, S1, remains "on" during the energizing portion of the phase. On the other hand, if the signal generator or microprocessor outputs a hard chopping signal, that signal is applied to both switches simultaneously.

FIG. 4C shows the PWM signal G1 which supplies current to the phase windings according to the current profile P1. Signal G1 has a constant frequency and a constant duty cycle over the entire phase energization time from time To to time Tc. The average voltage curve A1 shows the average voltage of the PWM waveform supplied to the phase during the phase energizing time, which is a constant value over the entire phase energizing time. To achieve the current profile P2 according to the invention, the PWM signal supplied to the windings, ie the signal G2 (see FIG. 4E), may be controlled in a number of different ways. In FIG. 4E, the frequency of the operating signal is constant, but its duty cycle is variable. As shown in FIG. 4 (E), from time To to time Tx, the operating signal starts at the first value and has a gradually decreasing duty cycle over this interval. The operation signal has a constant duty cycle from the time Tx to the time Tc. However, this duty cycle is shorter than the duty cycle of the operating signal supplied to one or both switches from time To to time Tx. The average voltage curve of the PWM signal supplied to the phase in the phase energized portion thus has a first portion where the average voltage is substantially higher than the average voltage of the second portion. The lengths of the first and second parts correspond respectively to the time of a variable and constant duty cycle of the PWM signal supplied to the phase. This is important. This is because, by the time Tx, in order to increase the current to the desired peak value Ip ', the average voltage input to the phase is substantially higher than the average voltage supplied otherwise. This means that it must be a value.

7 (A) to 7 (C), FIG. 7 (A) particularly shows the waveform of another PWM operation signal corresponding to the operation signal shown in FIG. 4 (E). ing. According to this waveform, the duty cycle of the operation signal is initially the first value in the section from the time point To to the time point Tx, and then gradually decreases. Also, in the section from time Tx to time Tc, the operation signal has a constant duty cycle shorter than the duty cycle of any operation signal supplied to the switch device in the section from time To to time Tx. Figure 7 (B) illustrates another method of achieving the same result, i.e., supplying a significantly higher voltage to the phase during the first portion of the phase energization time, which is a duty cycle. Includes providing a PWM signal with a constant but variable frequency. The frequency starts at a predetermined frequency and gradually increases from time To to time Tx. In the section from the time Tx to the time Tc, the operating signal has a constant frequency higher than the frequency of any operating signal supplied to the switch device from the time To to the time Tx. Further shown in FIG. 7C is a third method of providing a fairly high voltage to the phase during the first portion of the phase energization time, which method is variable in both duty cycle and frequency. It includes providing a PWM signal. Regardless of how the frequency and duty cycle of the operation signal change from time To to time Tx, the operation signal has a constant frequency and a constant duty in the section from time Tx to time Tc. Have a cycle.

What has been described above is a control method and apparatus for manipulating the current profile in each phase of a single-phase or multi-phase SRM. The circuit that accomplishes this control strategy controls the current profile in the energized portion of each phase to reduce motor noise. Also, in the circuits and methods of the present invention, either hard chopping or soft chopping current control methods may be used to control the current profile. In operation, the current level is first raised to a higher peak than normal. The current is then reduced from its peak value to the same current level as normal when the phase is de-energized. As a result, the slope of the current profile when the phase is de-energized is much gentler than in other cases. The controller and method of the present invention are easily incorporated into existing SRM control circuits and may include a microprocessor. According to the method of the present invention, the PWM current is controlled to control the current flowing through the phase winding when the phase is in an energized state, thereby quickly raising the current to its peak value at the beginning of the energizing time of the phase. The signal duty cycle is used. Also, the frequency of the PWM signal is changed to achieve the same result. Also, both the duty cycle and frequency of the PWM signal may be changed to achieve the same result. In the electric motor, the change of the leveled elliptical deformation force acting on the electric motor when the phase of the electric motor changes from the energized state to the deenergized state is moderated, thereby reducing ringing in the electric motor. Correcting the normal force generated is one advantage of the control method and apparatus of the present invention.

From the above description, it will be appreciated that the several objects of the invention are achieved and other advantageous results are obtained.

Although the present invention has been described in detail above with reference to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art that it is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first circuit of the present invention for manipulating the current profile of the current supplied to the windings of an SRM in the energized portion of a phase.

FIG. 2 is a block diagram showing a second circuit of the present invention for manipulating a current profile.

3A and 3B respectively show waveforms of a soft chopping PWM signal and a hard chopping PWM signal for controlling a current supplied to a winding.

FIG. 4A is a graph showing phase winding inductances in a phase energizing portion and a deactivating portion of an electric motor,
(B) shows one typical current profile in the energized portion of the phase, and (C) shows the PWM signal and its average voltage used to generate the current profile of (B). (D) shows the current profile generated by the circuit of the present invention, and (E) shows (D).
Used to generate the current profile of the
The signal and its average voltage are shown.

5A is a vertical force in the motor in the biasing portion of the phase and the phase is in a de-energized state for the case where the current profile for the motor corresponds to the profile of FIG. 4B. Figure 4B shows the ringing that is generated, (B) the normal force in the motor and the phase deenergization in the energized portion of the phase for the case where the current profile for the motor corresponds to the profile of Figure 4 (D). It shows the ringing that occurs when the state is reached.

FIG. 6 shows the forces generated in the motor as the rotor poles of the motor pass through the stator poles, in particular (A) for the case where the two poles are not aligned with each other, (B).
Shows the case where the two poles are aligned with each other.

7 illustrates various PWM signals that can be used by the circuit of the present invention to obtain the current profile of FIG. 4 (D).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Device of this invention 12 ... Switch device 14 ... Hall effect sensor 16 ... Signal generator (PWM signal generator) 18 ... Control device 20 ... Microprocessor M ... Switching reaction motor S ... Stator assembly R ... Rotor assembly

Claims (37)

[Claims] Claim: What is claimed is: 1. A device for controlling the current profile in the energized portion of a single-phase or multi-phase SRM, comprising a phase winding and a switch for directing current to said winding when the phase is energized. A device, a detector for detecting an operating state of the SRM, a signal generator for supplying an operating signal for controlling a current to the winding to the switch device, and the signal generator according to a predetermined profile A controller for controlling the signal generator in response to the detector to output an operating signal having an operating characteristic of supplying current to the phase in the predetermined profile. The current is rapidly increased from zero to a peak value when entering the state, and then decreases to a second value below the peak value below the peak value by the time the phase is de-energized, and the current is phase When in the de-energized state, it decreases from the second value to 0, so that the change that occurs in the current profile when the phase switches from the energized state to the de-energized state is not an abrupt change but this abrupt change. A device configured to reduce the degree of ringing that typically occurs in a motor when the supply of current to the winding is stopped by a change that is not, thereby reducing the noise of the motor. 2. The device of claim 1, wherein the switch device includes first and second switches, the first and second switches being provided on respective sides of the phase winding. And each switch is turned on when the phase is energized and a current can flow to the winding, and at least one of the first and second switches is activated by an operation signal from the signal generator. Controlled device, whereby the operation of the switch is controlled as a function of the signal characteristic of the operating signal. 3. The device according to claim 2, wherein the first and second switches are controlled by the operation signal from the signal generator, whereby the operations of the first and second switches are controlled by the operation signal. A device characterized in that it is controlled as a function of the signal characteristics of the operating signal. 4. The apparatus of claim 2 or 3, wherein the signal generator includes a PWM signal generator, the pulse width, duty cycle and frequency of the PWM signal are the operating characteristics of the SRM and the phase energization. A device characterized in that it is a function of the desired current profile to be generated when in the state. 5. The apparatus of claim 2 or 3, wherein said controller comprises a microprocessor, said microprocessor receiving inputs relating to the operation of said SRM, said inputs and said phase being energized. Device for controlling the signal characteristic of the operating signal generated by the signal generator as a function of the desired current profile to be generated at times. 6. The apparatus of claim 4 wherein said controller is responsive to input from said detector when said phase is energized such that the duty cycle is initially at a length. And a duty cycle of the PWM operating signal generated by the signal generator is varied such that the current gradually decreases as it rises above zero until it reaches the peak value of the current profile. . 7. The apparatus of claim 6 wherein said controller is further responsive to input from said detector when said phase is energized, causing current to reach said peak value of said current profile. A device for maintaining a constant duty cycle of the PWM operating signal generated by the signal generator from a point in time until the phase is de-energized. 8. The apparatus of claim 4, wherein the controller is responsive to input from the detector when the phase is energized, the frequency being initially at a frequency. A device for varying the frequency of the PWM operating signal generated by the signal generator such that the current gradually increases as it rises above zero until it reaches the peak value of the current profile. 9. The apparatus of claim 8 wherein said controller is further responsive to input from said detector when said phase is energized, causing current to reach said peak value of said current profile. A device for maintaining a constant frequency of the PWM operation signal generated by the signal generator until the phase is de-energized from a time point. 10. The apparatus of claim 4 wherein said controller is responsive to input from said detector when said phase is energized, wherein frequency and duty cycle are initially at a certain level. The frequency and duty cycle of the PWM operating signal generated by the signal generator such that the current changes as the current rises above zero until it reaches the peak value of the current profile. Device to do. 11. The apparatus of claim 10 wherein said controller is further responsive to input from said detector when said phase is energized such that current reaches said peak value of said current profile. A device, characterized in that the frequency and duty cycle of the PWM operating signal generated by the signal generator are kept constant from the time point until the phase is de-energized. 12. The apparatus of claim 5, wherein said microprocessor is responsive to various inputs indicative of the operating state of said motor when said phase is energized, in frequency and duty of said PWM operating signal. Controlling one or both of the cycles such that the frequency or duty cycle, respectively, is initially at a certain value and changes as the current rises above zero until the peak value of the current profile is reached. An apparatus characterized by changing a frequency or a duty cycle of a PWM operation signal. 13. The apparatus of claim 12, wherein said microprocessor is further responsive to said input when said phase is energized, said phase being at a point when current reaches said peak value of said current profile. Until P becomes inactive
An apparatus characterized in that the frequency and duty cycle of the WM operating signal are kept constant. 14. The apparatus of claim 2 wherein said controller drives said signal generator to generate an operating signal for soft chopping the current during the energizing time of said phase. A device characterized by the above. 15. The apparatus of claim 3 wherein the controller drives the signal generator to generate an operating signal that hard chops current during an energizing time when the phase is energized. A device characterized by the above. 16. The device according to claim 1, wherein the detection device is a Hall effect sensor. 17. A device for controlling the current profile in the energized portion of a single-phase or multi-phase SRM, comprising a phase winding and a switch for directing current to said winding when the phase is energized. A device comprising first and second switches, said first and second switches being provided on respective sides of said phase windings, said first and second switches being said phase switches. A switch device that is turned on when a current is allowed to flow to the winding, a detection device that detects the operating state of the SRM, and a PWM operation signal that controls the current to the winding. To the switch device and the actuation signal is applied to the switch to control at least one of the first and second switches, whereby the actuation of the switch is a function of the signal characteristics of the actuation signal. A signal generator to be controlled, and controlling the signal generator in response to the detector to output an operating signal having an operating characteristic that the signal generator supplies current to the winding according to a predetermined profile. A controller, wherein in the predetermined profile, the current is rapidly increased from zero to a peak value when the phase is energized, and thereafter the phase is deenergized. It decreases to a second value below the peak value, and the current decreases to 0 below the second value when the phase is deactivated, which causes the phase to deactivate from the energized state. The degree of ringing that generally occurs in a motor when the supply of current to the winding is stopped by this non-abrupt change, rather than the abrupt change in the current profile that occurs when switching to the energized state. Device configured to reduce the noise of the electric motor. 18. The apparatus according to claim 17, wherein the first and second switches are controlled by the operation signal from the signal generator, whereby the operation of the first and second switches is controlled by the operation signal. A device characterized in that it is controlled as a function of the signal characteristics of the operating signal. 19. The apparatus according to claim 17, wherein said controller is responsive to an input from said detector when said phase is energized to provide one or more of frequency and duty cycle of said PWM operating signal. Of both the PWM operating signal such that the frequency or duty cycle is initially at a certain value and changes as the current rises above zero until the peak value of the current profile is reached. A device characterized by varying frequency or duty cycle. 20. The apparatus of claim 19, wherein said controller is further responsive to said detector when said phase is energized, said current from said time point being at said peak value of said current profile. A device characterized in that the frequency and duty cycle of the PWM operating signal are kept constant until the phase is de-energized. 21. The apparatus of claim 20, wherein the controller drives the signal generator to generate an actuation signal for soft chopping the current during the energizing time of the phase. A device characterized by the above. 22. The apparatus of claim 20, wherein the controller drives the signal generator to generate an operating signal that hard chops current during an energizing time when the phase is energized. A device characterized by the above. 23. A device for controlling the current profile in the energized portion of a phase of a single-phase or multi-phase SRM, comprising a phase winding and a switch for directing current to said winding when the phase is energized. A device comprising first and second switches, said first and second switches being provided on corresponding sides of said phase windings, said first and second switches said A switch device that is turned on when a current is allowed to flow to the winding in an energized state, a detection device that detects various operating parameters of the SRM, and a switch device that is responsive to the detection device Control the current of P
A WM actuation signal is provided to the switch device, the actuation signal being provided to the switch to control at least one of the first and second switches, thereby providing current to the winding according to a predetermined profile. And a microprocessor whose operation is controlled as a function of the signal characteristics of the operating signal so that in the given profile the current is greater than zero when the phase is energized. Is rapidly increased to a second value below the peak value by which time the phase is de-energized, and the current is reduced to a second value when the phase is de-energized. It decreases from a value of 2 to 0, so that the change that occurs in the current profile when the phase switches from the energized state to the de-energized state is not an abrupt change,
A device configured to reduce the degree of ringing that generally occurs in an electric motor when the supply of current to the winding is stopped by this non-abrupt change, thereby reducing the noise of the electric motor. 24. The apparatus according to claim 23, wherein the first and second switches are controlled by the operation signal from the microprocessor, whereby the operations of the first and second switches are performed by the operation. A device characterized in that it is controlled as a function of the signal characteristics of the signal. 25. The apparatus of claim 24, wherein said microprocessor is responsive to an input from said sensing device when one of said phases is energized, one or more of a frequency and a duty cycle of said PWM operating signal. Of both the PWM operating signal such that the frequency or duty cycle is initially at a certain value and changes as the current rises above zero until the peak value of the current profile is reached. A device characterized by varying frequency or duty cycle. 26. The apparatus of claim 25, wherein said microprocessor is further responsive to said sensing device when said phase is energized, said current from the time when said current reaches said peak value of said current profile. A device characterized in that the frequency and duty cycle of the PWM operating signal are kept constant until the phase is de-energized. 27. The apparatus of claim 23, wherein the microprocessor generates an operating signal that soft chops the current during the energizing time that the phase is energized. 28. The apparatus of claim 23, wherein the microprocessor generates an operating signal that hard chops current during an energizing time when the phase is energized. 29. A method of controlling the current profile in the energized portion of a phase of a single-phase or multi-phase SRM, the winding being switched to incorporate the phase winding into the circuit when the phase is energized. Directing current to a wire, generating an operating signal used to control the current supplied to the winding, and operating characteristics of the operating signal supplying current to the winding according to a predetermined profile. Controlling the operating characteristics of the operating signal so that the current is zero when the phase is energized in the predetermined profile.
More rapidly to a peak value and then decrease to a second value below the peak value below the peak value by the time the phase is deactivated, the current being To 0 from the second value so that the change in the current profile that occurs when the phase switches from the energized state to the de-energized state is not an abrupt change, but this non-abrupt change causes the winding Reducing the degree of ringing that commonly occurs in a motor when the supply of current to the line is stopped, thereby reducing the noise of the motor. 30. The method of claim 29, wherein the step of generating an operating signal comprises generating a PWM operating signal. 31. The method of claim 30, wherein the PWM
The process of generating the operating signal is a variable duty cycle P
Generating a WM operating signal, the duty cycle being initially of a certain length and gradually decreasing as the current rises above zero until the peak value of the current profile is reached. how to. 32. The method of claim 31, wherein the PWM
The step of generating an operating signal comprises generating a PWM operating signal of constant duty cycle from the time when the current reaches the peak value of the current profile until the phase is de-energized. Method. 33. The method of claim 30, wherein the PWM
The step of generating the operating signal includes generating a variable frequency PWM operating signal, the frequency being initially at a frequency, as the current rises above zero until the peak value of the current profile is reached. A method comprising generating a gradually increasing PWM operating signal. 34. The method of claim 33, wherein the PWM
The step of generating an operating signal comprises generating a constant frequency PWM operating signal from the time when the current reaches the peak value of the current profile until the phase is de-energized. . 35. The method of claim 30, wherein the PWM
The step of generating the operating signal comprises generating a signal of variable frequency and duty cycle, the frequency and duty cycle being initially at a certain value, until the current reaches the peak value of the current profile. A method characterized by changing as it rises above zero. 36. The method of claim 35, wherein the PWM
The step of generating an operating signal further comprises generating a signal of constant frequency and duty cycle from the time the current reaches the peak value of the current profile until the phase is de-energized. And how to. 37. A method of controlling the current profile in the energized portions of a single-phase or multi-phase SRM, the winding being switched to incorporate the phase winding into the circuit when the phase is energized. Directing current to a wire, generating an operating signal used to control the current supplied to the winding, and causing the current in the phase to peak above zero when the phase is energized. To a second value lower than the peak value until the phase is de-energized, and then the current when the phase is de-energized. Lowering from the second value to 0,
And increasing the current from zero to a peak value, wherein the step of increasing the average voltage of the operating signal used to control the current supplied to the winding is such that Has a value higher than the average voltage of the operating signal used to control the current supplied to the winding in the interval where it drops to a value such that the phase is deenergized from its energized state. The change in the current profile that occurs when switching to the state is not a sudden change but a gentle change, and due to this gentle change, the ringing that generally occurs in the electric motor when the current supply to the winding is stopped. A method to reduce the degree of noise and thus the noise of the motor.