WO2017030509A1

WO2017030509A1 - Method and apparatus for energy recoverying of a dc motor

Info

Publication number: WO2017030509A1
Application number: PCT/SK2016/050008
Authority: WO
Inventors: Petro FISENKO; Tibor KOZINKA; Ľubomír BUKOVÝ
Original assignee: Energon Sk S.R.O.
Priority date: 2015-08-20
Filing date: 2016-08-10
Publication date: 2017-02-23
Also published as: SK50382015A3

Abstract

A DC motor with energy recovery comprising a rotor (3) with an output shaft (11) for transmitting torque to machinery or energy systems, a stator (9) further comprising an n-component system of serial stator excitation coils (1), an n-component system of serial stator induction coils (14) and an n-component system of ferrite cores (2) arranged so that at each of the ferrite cores (2) there is always one stator excitation coil (1) and one stator induction coil (14). It further comprises a rotor (3) fitted at the circumference of which is an n- component system of permanent magnets (4) with the same polarity orientation. The first stator excitation coil (1) is connected to a positive feeder terminal (+UB) and the last stator excitation coil (1) is connected through a switching leg with a control/switching circuit (6) to a negative feeder terminal (-UB). The first stator induction coil (14) is connected through an energy recovery leg (8) to the positive feeder terminal (+UB) and the last stator induction coil (14) is connected to the negative feeder terminal (-UB).

Description

METHOD AND APPARATUS FOR ENERGY RECOVERYING OF A DC MOTOR

Field of i nvention

The present invention relates to an excitation and continuous energy recovery of a DC motor for driving energy systems/mach inery in particular for intensified electricity generation or intensified work doing . The invention also relates to a DC motor with energy recovery based on the above method to be used namely in conju nction with electricity generators or alternators. The purpose of the present invention is to utilize, as much as possible, the energy potential of an electric power accumulator and the self-induced electromotive voltage of inductances by means of a specially developed device. The invention relates to the field of energy.

Prior art

Well known in the prior art is the principle of the Adams motor that utilizes more efficiently the energy consumed to excite stator coils. I n conventional motors the self-induced voltage of the opposite polarity in stator coils is not utilized and it is only converted to heat. The Adams motor design comprises a stator made of C-cores and a coil. A rotor with permanent magnets moves in the gap between the C-cores. All permanent magnets have the same S-N polarization direction and the coil is wired to repel the rotor magnets. When the coil is not energized , one of the magnets in the rotor is attracted to the gap between the C- cores. Once the coil is energized , the magnet is repelled from the gap making the rotor tu rn . The coil is excited by pulses based on the rotor position . The motor is driven by DC pulses, the advantage of wh ich is that, unlike in conventional motors, there are no hysteresis losses in the stator core. Another advantage is that the coil responds to de- energizing by speeding up the rotor rather than acting against its motion . A disadva ntage of the Adams motor is that the power and the overall efficiency of the motor rapid ly fall with decreasing speed .

The above d isadvantages of electricity generation, having regard to otherwise unused electromotive self-ind uced voltage of ind uctances generated by electric DC motors, made room for developing such a method and a device design used in particular for intensified electricity generation that would utilize the prod uced electromotive self-induced voltage of inductances in electric DC motors in a different way rather than just to do work as it is known in the prior art.

This effort resulted in a method of DC motor excitation and energy recovery and a DC motor with energy recovery as described in the present invention.

Summary of the invention

The above drawbacks are eliminated by a method of DC motor excitation and energy recovery intended for energy systems/machinery and in particular for intensified electricity generation or intensified work doing accord ing to the present invention , the essence of which lies in the fact that the actual method of DC motor excitation and energy recovery runs in two repeated stages, where:

- in the first stage:

- the stator excitation coils are energized by electrical excitation pulses from an accumulator voltage;

- force effects prod uced by the electrical excitation pulses in magnetic circuits of the stator excitation coils cause magnetic circuits of the rotor to deflect by an angle alpha;

- the transformer effect in evenly spaced stator ind uction coils induces a secondary voltage;

- in the second stage: when the accumulator voltage is interrupted , inverse electromotive voltage is ind uced in the evenly spaced stator ind uction coils ;

energy is being continuously recovered and the overall inverse electromotive voltage recharges the accumulator.

The above method of DC motor excitation and energy recovery intended for energy systems/machinery and in particular for intensified electricity generation or intensified work doing accord ing to the present invention , the essence of which lies in the fact that in addition to having a rotor with an output shaft for transmitting torque to machinery or energy systems , its stator comprises an n-component system of serial stator excitation coils , an n-component system of serial stator induction coils and an n-component system of ferrite cores arranged so that at each of the ferrite cores there is always one stator excitation coil and one stator ind uction coil. It further comprises a rotor, fitted at the circumference of which is an n-component system of permanent magnets, for example of the NdFeB type, with the same polarity orientation , e.g . N . The first stator excitation coil is connected to the positive feeder terminal, to which the accumulator is connected and the last stator excitation coil is connected th rough the switching leg with a control/switching circuit to the negative feeder terminal, to which the accumulator is connected . The control/switching circuit comprises a Hall effect or similar sensor, or the control/switching circuit has a control input, to which the Hall effect or similar sensor is con nected . The Hall effect or similar sensor is fitted between two adjacent stator excitation and/or induction coils. The first stator ind uction coil is connected through the energy recovery leg to the positive feeder terminal and the last stator induction coil is connected to the negative feeder terminal . The energy recovery leg comprises at least one semiconductor rectifier element or voltage multiplier. The efficiency of the device can be improved by connecting the point of the last excitation coil to the control/switch ing circuit, which feeds to a protection circuit having one end connected to the negative feeder terminal and the other end connected to the first stator excitation coil . The protection circuit comprises a capacitor and a series combination of a resistor and a diode.

The rotor fitted at its surface with permanent magnets of identical orientation ensures continuous rotation due to the effect of excitation electrical pulses produced in the stator excitation coils. The rotor may be of a cylindrical, disc or in special cases also of a lever-arm design, i.e. it is comprised of a set of arms coupled in the axis of rotation .

From the structu ral point of view, an alternative is possible where an n-component system of stator excitation and induction coils with an n-component system of ferrite cores is fitted radially to the stator circumference and the n-component system of permanent magnets is fitted rad ially to the rotor circumference. I n another alternative an n- component system of stator excitation and ind uction coils with an n- component system of ferrite cores is fitted axially at the stator circumference and the n-component system of permanent magnets is fitted axially at the rotor circumference. The magnetic circuit of the stator is not closed . The strength of the field generated by the permanent mag nets affects the speed of the connected mach inery, such as an electricity generator, which creates motion inertia and that is why a choice of material of permanent magnets and ferrites is important and so is the distance between the permanent magnets of the rotor and the ferrite magnets stator.

Thus, the d rive unit comprises a control/switching circuit controlling the feeding of pulse current to the stator excitation coils. The self-induced (inverse) electromotive voltage is taken off the stator inductance coils to the energy recovery circuit, i .e. it is designed for accumulator charging . The control/switching circuit functions as an operation mode support so a square wave current with a mark to space ratio of 1 : 1 flows through the stator excitation coil to achieve maxim um performance of the machine - the effective d rive un it. Pulse timing is determined by the characteristics of the generator con nected to the rotor, i.e. the speed of rotation , position of the permanent magnets of the rotor relative to the magnetized poles of the stator excitation coil cores, as well as the distance in which the magnets move when they pass the poles of the stator coil cores. By changing (sizing) the lengths of levers in the rotor lever system (if it is of such a design) or conventionally by sizing the rotor rad ius already when designing the machine one can set the controllable force requ ired to produce torque. To understand the principle, we further provide an explanation for a single stator coil on ly. As soon as the stator excitation coil is connected to the accumulator voltage current starts to exponentially rise from zero to a specific value. After transients subside, constant d irect current of a specific value flows through the stator excitation coil . The stator excitation coil thus contains energy equal to the work exerted to charge it. As a result of the change in the current flowing in the stator excitation coil a secondary voltage of a reverse polarity is induced through the transformer effect in the stator ind uction coil. I .e. if at the point B there is a voltage of positive polarity, at the point E there is a voltage of negative polarity. For th is secondary voltage the d iode in the energy recovery leg is closed , wh ich means that no current flows through the induction coil. When the accumulator power supply circuit is disconnected , i.e. when the control/switching circuit in the switching leg is d isconnected , the energy stored in the stator induction coil is discharged through the energy recovery circuit, th us charging the connected accumulator. This means that by timing the excitation of the stator excitation coils and the control/switching circuit in the switching leg we achieve that the energy accumulated in the stator excitation coils while it was connected to the power source - i .e. accumulator, does work and prod uces torque for the connected machinery namely for electricity generation . And again, when charging the stator induction coils that are magnetically coupled to the stator excitation coils we achieve that the energy accumulated in the stator induction coils as a result of reverse electromotive voltage will recharge the accum ulator using the recovered energy when the power source - the accumulator is disconnected. These are substantial benefits of the DC motor with energy recovery.

As far as the design of a DC motor with energy recovery is concerned , it is clear that the stator is provided with a term inal box with terminals for connecting the accumulator and possibly also terminals for connecting a sem iconductor rectification element or a voltage multiplier for the energy recovery leg. Furthermore, the terminal box can also house terminals for connecting components of the protection circuit, i.e. a capacitor, a resistor and a d iode. Part of the components or the control/switching circuit can be housed in the terminal box or in a superstructure of a DC motor.

To finally use a DC motor with energy recovery to power energy systems , in particular those for intensified electricity generation , it is sufficient just to fit the rotor of the DC motor with linking components such as a coupling to connect the rotor with an electric generator or an alternator. In another alternative design it is possible that the rotor of a DC motor with energy recovery is an integral part - e.g . a rotor or another part of the electric generator or the alternator. As an example, a 3-phase low-speed permanent mag net generator with an inner stator can be used , i.e. a generator with a rotating outer body or a gearbox with a high-speed generator.

For another final use of a DC motor with energy recovery for driving machinery and in particular for intensified work doing it is important that the rotor of the DC motor with energy recovery was fitted with linking components, e.g. a coupling or a flange connection for connecting to the rotor of the driven machinery, such as a pump, compressor, fan , etc. In another alternative design the rotor of the DC motor with energy recovery can be one part with the rotor of the machinery d rive element.

The functioning of the DC motor with energy recovery can also be described as follows. If the stator excitation coils are not energized , what acts on the rotor is only the attraction between the cores of the stator excitation coils and rotor permanent magnets, i .e. positions of stator excitation coils and rotor permanent magnets are identical. As soon as the accumulator is energized the stator excitation coils receive a current pulse allowing the rotor to overcome the dead centre and resistance of the coupled generator or other machinery. This creates torque. The rotation speed detected by a control sensor such as a Hall effect sensor prod uces a signal that is transmitted to the control/switching circuit, where it is processed into a short pulse of up to about 1 0 ms and suitable polarity, which is then discharged to the stator excitation coils , resulting in continuous rotation of the rotor together with the electric generator located on the support frame of the DC motor stator and possibly attached by anti-vibration mounts. The slope of the increase and the intensity of electric current in the stator excitation coils at constant resistance usually depend on the supply voltage. That is why the control/switching circuit includes speed control to multiply the supply voltage. When the stator excitation coils are between the rotor permanent magnets, the Hall effect sensor does not produce any signal to the control/switching circuit causing the stator excitation coils to discharge to the recovery circuit for accumulator charging. I n this mode, the rotor of the DC motor with energy recovery can turn together with an electric generator and thus generate electric power for the consumer for as long as required , until the stator excitation coils are disconnected from the power supply or until the accumulator is disconnected , i.e. DC motor with energy recovery is switched off. The benefits of the method of DC motor excitation and energy recovery for d riving energy systems/machinery in particular for intensified electricity generation or intensified work doing and a DC motor with energy recovery based on that method according to the present invention are apparent from its effects exh ibited externally. The effects of the present invention lie namely in the fact that in addition to doing mechanical work by means of the produced torque, the generated self-induced electromotive inductance voltage of stator inductance coils in pulse controlled DC motors is utilized for the power supply energy recovery and possibly for generation of additional power supplied to the power supply system , thus sign ificantly increasing the efficiency and utility of the device.

The invention based on the method of autonomous electric power supply utilizing a specific hybrid system of an adaptive electromagnetic motor-generator with ancillary circuits addresses domestic, techn ical, economic, social and environmental issues associated with independent power supply of various devices in commercial and private buildings, family houses, suburban homes, heating systems, yachts, boats, electric cars and so on . A DC motor with energy recovery coupled with an electric generator produces a unique autonomous uninterruptible power supply that gets to the state of optimum performance with a minimal delay after start. It is characterized by a quiet operation and due to its compact design it takes up minimum space. It has minimum maintenance requirements with a period of 2 years between outages for battery/accumulator replacement and inspection and maintenance of bearings. A DC motor with energy recovery coupled with an electric generator is versatile, because it can be integrated into existing systems of standby power supplies without any major modifications . Brief descri ption of drawings

The method of DC motor excitation and energy recovery intended for energy systems/machinery, in particular for intensified electricity generation or intensified work doing , and a DC motor with energy recovery based on that method according to the present invention will be explained in greater detail by means of specific embodiments shown in drawi ngs, where Fig. 1 shows the configuration of the motor part - the stator and the rotor of a pulse controlled DC motor with energy recovery. Fig . 2 shows a wiring diagram of the excitation and recovery circuit of such a DC motor connected to an accum ulator. Fig . 3 shows a wiring diagram of the excitation and recovery circuit of such a DC motor connected to a power generator.

Description of the preferred embodiments

It is understood that the ind ivid ual embodiments of the method of DC motor excitation and energy recovery intended for energy systems/machinery in particular for intensified electricity generation or intensified work doing accord ing to the present invention are shown by way of illustration only and not as limitations. Those skilled in the art will be able to ascertain, using no more than routine experimentation , many equivalents to the specific embodiments of the present invention . Such equivalents are intended to be encompassed by the following claims.

Those skilled in the art would have no problem dimension ing such DC motor with energy recovery and choosing suitable materials and design configurations, which is why these features were not designed in detail. Example 1

I n this example of an embodiment of the invention describes a method of DC motor excitation and energy recovery intended for energy systems/mach inery and in particular for intensified electricity generation or intensified work doing , the functioning of wh ich is apparent from Figs. 1 and 2. The actual excitation and energy recovery runs in two stages, where:

- in the first stage:

- stator excitation coils are energized by electrical excitation pulses i(t) from an accumulator voltage +U B ;

- force effects prod uced by the electrical excitation pulses [(t) in magnetic circuits of the stator excitation coils 1_ cause magnetic circuits of the rotor to deflect by an angle alpha ;

- the transformer effect in evenly spaced stator induction coils 1_4 ind uces a secondary voltage;

- in the second stage:

- when the accumulator voltage + LJ_B is interrupted , an inverse electromotive voltage LJ em is induced in the even ly spaced stator ind uction coils 14.;

- energy is being continuously recovered and the overall inverse electromotive voltage LJ em recharges the accumulator.

Example 2

This example of a particular embod iment of the invention describes the design of a DC motor with energy recovery as shown in Figs. 1 and 2. It comprises a stator 9, a rotor 3 and an output shaft 1_i for transmitting torque to machinery or energy systems, which parts form the motor assembly of the DC motor with energy recovery. The stator 9 further comprises a 12-component system of serial stator excitation coils 1_, a 12-component system of serial stator induction coils 14 and a 12-component system of ferrite cores 2 arranged so that at each of the ferrite cores there is always one stator excitation coil 1 and one stator induction coil ΛΑ_. Rotor 3 further comprises at its circumference a 12-component system of the NdFeB type of permanent magnets 4 with identical polarity orientation N.. The system size is limited only by design limits for the defined radius of the rotor 3. The first stator excitation coil 1 is connected in the node B to a positive feeder terminal + U.B, to which the accumulator 7 is connected and the last stator excitation coil is connected through a switching leg with a control/switching circuit 6 to a negative feeder terminal -UB, to which the accumulator 7 is connected. The control/switching circuit 6 has a control input C to which a Hall effect sensor 1_0 is connected. Alternatively, the Hall effect sensor 1_0 is an integral part of the control/switching circuit 6. The Hall effect sensor 0 is fitted between two adjacent stator excitation and/or induction coils 1_, 1_4. The first stator induction coil 1_4 is connected in the node E through an energy recovery leg 8 to the positive feeder terminal +UB and the last stator induction coil 1_4 is connected in the node D to the negative feeder terminal -UB. The energy recovery leg 8_ comprises a semiconductor rectifier element D2, or alternatively a voltage multiplier. Furthermore, a connection exists between the last excitation coil 1 in the node A and the control/switching circuit 6, which feeds to a protection circuit 5. having one end connected to the negative feeder terminal -LJB and the other end connected to the first stator excitation coil 1_. The protection circuit comprises a capacitor C_b and a series combination of a resistor Rb and a diode Di. The rotor 3 is of a disc design, where in the stator 9 a 12-component system of stator excitation and induction coils 1_, 1_4 with a 12-component system of ferrite cores 2 is fitted radially to the circumference of the stator 9. The rotor 3 comprises a 12-component system of permanent magnets 4 fitted radially to the circumference of the rotor 3.

In another alternative, the stator 9_ comprises a 12-component system of stator excitation and induction coils 1_, 1_4 with a 12- component system of ferrite cores 2 fitted axially at the circumference of the stator 9 and the rotor 3 comprises a 12-component system of permanent magnets 4 fitted axially at the circumference of the rotor 3.

Example 3

This example of a particular embodiment of the invention describes one application of a DC motor with energy recovery designed for use with energy systems - an electric generator for intensified electricity generation as shown in Fig. 3. The design and circuit wiring of a DC motor with energy recovery are sufficiently described in Example 2. Extending from the rotor 3 of a DC motor with energy recovery is an output shaft H, mechanically connected to which is an energy system - an electric generator 1_3. The electrical output from the electric generator 1_3 is fed to a rectifier unit 1_2 and the control unit 15, from which it is connected to the positive and negative feeder terminals + UB, -LJB. A large capacity electricity accumulator 7 is also connected to the positive and negative feeder terminals + UB, -LJB. The output electrical leg of the power generator 1_3 continues through the voltage converter 1_6 to the external power supply system.

Example 4

This example of a particular embodiment of the invention describes another application of a DC motor with energy recovery designed for driving a machinery, in general with a rotary drive for intensified work doing. The design and circuit wiring of a DC motor with energy recovery are sufficiently described in Example 2. Extending from the rotor 3 of a DC motor with energy recovery is an output shaft 1_1, mechanically connected to which is a rotor of a machine, such as a pump, compressor, fan, etc. Industrial applicability

The method of DC motor excitation and energy recovery and a DC motor with energy recovery according to the present invention find their application namely in the energy industry.

Claims

1 . A method of DC^! motor ^' excitation and energy recovery, characterised in that the excitation and the energy recovery runs repeatedly in two stages, where:

- in the first stage:

stator excitation coils (1 ) are energized by electrical excitation pulses (i(t)) from an accumulator voltage (+U B) ;

force effects produced by the electrical excitation pulses (i(t)) in magnetic circuits of the stator excitation coils ( 1 ) cause mag netic circuits of the rotor to deflect by an angle (alpha);

the transformer effect in evenly spaced stator ind uction coils (14) ind uces a secondary voltage;

- in the second stage:

when the accumulator voltage (+U B) is interrupted , an inverse electromotive voltage ( U em) is induced in the evenly spaced stator induction coils ( 14);

energy is being continuously recovered and the overall inverse electromotive voltage ( Uem) recharges the accumulator.

2. A DC motor with energy recovery comprising a rotor with an output shaft for transmitting torque to machinery or energy systems, characterised in that the stator (9) comprises an n-component system of serial stator excitation coils (1 ), an n-component system of serial stator induction coils (14) and an n-component system of ferrite cores (2) arranged so that at each of the ferrite cores (2) there is always one stator excitation coil (1 ) and one stator induction coi l (14); it further comprises a rotor (3) fitted at the circumference of which is an n- component system of permanent magnets (4) with the same polarity orientation; the first stator excitation coil ( 1 ) is connected to a positive feeder terminal (+U B) and the last stator excitation coil (1 ) is connected through a switching leg with a control/switching circuit (6) to a negative feeder terminal (-UB); the first stator induction coil (14) is connected through an energy recovery leg (8) to the positive feeder terminal ( + UB) and the last stator induction coil (14) is connected to the negative feeder terminal (-UB).

3. A DC motor with energy recovery according to Claim 2, characterised in that the connection between the last excitation coil (1) in the node (A) and the control/switching circuit (6) feeds to a protection circuit (5) having one end connected to the negative feeder terminal (-UB) and the other end connected to the first stator excitation coil (1).

4. A DC motor with energy recovery according to Claims 2 and 3, characterised in that the control/switching circuit (6) comprises a Hall effect sensor (10) or the control/switching circuit (6) has a control input (C), to which the Hall effect sensor (10) is connected.

5. A DC motor with energy recovery according to Claim 4, characterised in that the Hall effect sensor (10) is fitted between two adjacent stator excitation and/or induction coils (1, 14).

6. A DC motor with energy recovery according to Claim 2, characterised in that the energy recovery leg (8) comprises at least one semiconductor rectifier element (D2) or a voltage multiplier.

7. A DC motor with energy recovery according to Claim 3, characterised in that the protection circuit (5) comprises a capacitor (Cb) and a series combination of a resistor (Rb) and a diode (Di).

8. A DC motor with energy recovery according to Claim 2, characterised in that the stator (9) comprises an n-component system of stator excitation and induction coils (1, 14) with an n-component system of ferrite cores (2) fitted radially to the circumference of the stator (9) and the rotor (3) comprises an n-component system of permanent magnets (4) fitted radially to the circumference of the rotor (3).

9. A DC motor with energy recovery according to Claim 2, c ha racterised i n that the stator (9) comprises an n-component system of stator excitation and ind uction coils (1 , 14) with an n-component system of ferrite cores (2) fitted axially at the circumference of the stator (3) and the rotor (3) comprises an n-component system of permanent magnets (4) fitted axially at the circumference of the rotor (3).