Vacuum pump system and method of energy regeneration

Abstract

A vacuum pump system (300), comprising at least one vacuum pump (330, 360) each comprising: a rotor (331, 361); a motor (332, 362) configured to drive the rotor (331, 361); and a converter (333, 363) configured to supply electrical power to the motor (332, 362) to accelerate and decelerate the rotor (331, 361). Each converter (333, 363) is further configured to: operate the motor 10 (332, 362) in a generator or braking mode for a deceleration of the rotor (331, 361); and capture as a regenerated energy at least a portion of the kinetic energy of the rotor (312, 361) during the deceleration.

Description

[0001] VACUUM PUMP SYSTEM AND METHOD OF ENERGY REGENERATION

[0002] FIELD OF THE INVENTION

[0003] The field of the invention relates to vacuum pump systems, and more specifically to methods of energy regeneration in vacuum pump systems.

[0004] BACKGROUND

[0005] Vacuum pumps are typically employed as a component of a vacuum system to evacuate working gases from the system. These pumps can be used to evacuate fabrication equipment used in, for example, the production of semiconductors, steel degassing, pharmaceutical, chemical industries and other applications.

[0006] Vacuum pump systems may comprise one or more vacuum pumps. These pumps may comprise primary pumps (i.e. , Screw pumps) and secondary pumps (i.e., Roots pumps). Primary pumps work against atmospheric pressure or a similar ‘high’ pressure, with secondary pumps extending the range of operation of primary pumps to lower ultimate pressures. Connecting several of these pumps in series can result in achieving lower working pressures. The precise number of pumps in a vacuum pump system will, however, ultimately depends on the particular application.

[0007] Each vacuum pump typically comprises a rotating mechanical element (also known as a rotor) that is driven by a respective motor and variable speed drive (also known as a frequency converter) module. The frequency converters can operate independently to monitor and vary electrical current, voltage, and speed of a respective electric motor.

[0008] During operation, the rotating mechanical element of, for instance, a primary pump, may be accelerated (also referred to as being Tamped up’) and operated at a particular rotational frequency until the primary pump achieves a certain pressure. The rotating mechanical element of a secondary pump may then be accelerated in a similar manner to achieve the working pressures for the particular application.

[0009] However, in certain scenarios, such as ‘load lock’ or with processes demanding varying pressures, the vacuum pumps in a vacuum pump system may need to be decelerated (also referred to as being ‘ramped down’ or ‘braking’) to a lower rotation frequency. This can be required multiple times during an operational cycle of the vacuum pump system. During such a scenario, the rotating high inertia mechanical elements of the vacuum pumps can possess a significant amount of kinetic energy prior to deceleration. This kinetic energy is typically wasted as dissipated heat during a deceleration operation.

[0010] Hence, it is desirable to provide a vacuum pump system and method of energy regeneration, that mitigates this issue.

[0011] SUMMARY OF THE INVENTION

[0012] In an aspect, there is provided a vacuum pump system, comprising: at least one vacuum pump each comprising: a rotor; a motor configured to drive the rotor; a converter configured to supply electrical power to the motor to accelerate and decelerate the rotor; wherein each converter is configured to: operate the motor in a generator or braking mode for a deceleration of the rotor; and capture as a regenerated energy at least a portion of the kinetic energy of the rotor during the deceleration.

[0013] In some embodiments, the vacuum pump system further comprises a controller configured to cause each converter of the vacuum pump system to operate the motor in the generator or braking mode for the deceleration of the rotor, and capture as the regenerated energy or at least a portion of the kinetic energy of the rotor during the deceleration.

[0014] When operating in the generator or braking mode, the kinetic energy of the rotor can be captured as regenerated energy in an alternative form, for instance as electrical energy. This can be achieved through control of the converter / s of the vacuum pump system. This tends to allow for better utilization of surplus energy during deceleration of a vacuum pump. The converters themselves control the motor current / voltage / frequency and hence the additional controls disclosed herein may be implemented directly in the converters themselves. This may be considered a ‘standalone’ mode of operation. However, an additional controller may interface with the converters and be utilised to converters to control the motors. This may be considered an ‘automatic’ mode of operation. The controller may adaptively control the converter / s of the vacuum pump system based on at least one of an amount of regenerated energy or power or current or voltage; an available energy or power or current or voltage from the converter / s; and a required energy or power or current or voltage. The required energy / power / current / voltage may be that required to maintain or achieve a particular operating condition of the vacuum pump system, for instance one or more vacuum pumps operating at a particular pump speed.

[0015] More specifically, each converter may be further configured to adaptively decelerate or brake the rotor, when in the generator or braking mode, over a required period, based on an available regenerative power. Such an adaptive monitoring and control scheme effectively decides the duration of the deceleration (the ramp down) to maximise energy availability / usage according to power requirements. For instance, there may be a requirement for handling a relatively high regenerative power, in which case the deceleration may be performed over a longer duration. Alternatively, there may be a requirement for a relatively lower regenerated power, in which case the deceleration may be performed quickly.

[0016] Such an adaptive control contrasts with operating the controller with a predetermined algorithm or program. By way of example, the controller may control the converter / s to directly use a portion of the regenerated energy in converter / s of other vacuum pumps of the vacuum pump system and to store the remainder of the regenerated energy in an energy storage means. As a further example, the controller may control the converter / s to store all the regenerated energy in an energy storage means. As a further example, the controller may control the converter / s to directly re-use all the regenerated energy without provided the regenerated energy to an energy storage means. It will be apparent that adaptive control of this nature tends to allow for the vacuum pump system to intelligently re-use regenerated energy according to the state of operation of the vacuum pump system at the current time, rather than being preconfigured to operate to use the regenerated energy in a specific manner irrespective of the actual real-time state of operation of the vacuum pump system.

[0017] The controller may be external to the converter / s and / or the drive electronics for a vacuum pump / vacuum pumps. More specifically, the controller may be a dedicated controller that monitors and manages the operation of the entire vacuum pump system. The vacuum pump system may comprise a plurality of vacuum pumps. The controller may take a holistic view of the entire system, to ensure that the entire system is managing and re-using regenerated energy effectively as the various vacuum pumps are accelerated and decelerated.

[0018] Some embodiments further comprise energy storage means. In such embodiments the converter is configured to capture the regenerated energy in the energy storage means. The energy storage means may preferably comprise at least one of: a capacitor bank; a battery; and a flywheel. The capacitor bank comprises a plurality of capacitors connected in series or parallel to form an energy storage means. The energy storage means may be inside the converter / s or drive electronics, or the energy storage means may be external to the converters or drive electronics. More specifically the energy storage means may be different to the capacitors found within the converter / s or drive electronics of vacuum pumps i.e., different to the DC-link capacitors. DC-link capacitors tend not to be configured or specified to store regenerated energy. By providing a dedicated energy storage means the energy storage means can be specified and tailored for the requirement of storing regenerated energy.

[0019] By capturing the regenerated energy in an energy storage means, the regenerated energy can be user later in the vacuum pump system. For instance, some regenerated energy may be used for real-time requirements to accelerate another vacuum pump, whilst some regenerated energy may be stored. Alternatively, all regenerated energy may be stored if power requirements to operate other vacuum pumps can be met easily from source AC power.

[0020] In some embodiments, each converter of the at least one vacuum pump comprises an electronic protection means. Preferably, the electronic protection means may be configured to provide at least one of: an under / over voltage protection for the respective vacuum pump; an over current protection for the respective vacuum pump; and an over temperature protection for the respective vacuum pump.

[0021] By providing each converter with its own electronic protection means, redundancy is provided to the vacuum pump system to ensure continual functioning of the vacuum pump system in the event of individual pump failures. For instance, different converters of different vacuum pumps may be manufactured against particular operational requirements and tolerances. Exceeding such tolerances, in operation, for instance through a transient event, could lead to the transient event propagating to other vacuum pumps in the vacuum pump system. By providing each vacuum pump with a respective electronic protection means tends to ensure faults are isolated at specific vacuum pumps, without propagating to and affecting other pumps in the system. Furthermore, this tends to avoid vacuum pump systems with architectures having single points of failure (such as, for instance, a common DC bus shared amongst vacuum pumps). The protection given is more generally based on voltage / current at the component level and temperature (at the component / system level) rather than a drive voltage or current provided to a specific vacuum pump.

[0022] In some embodiments, the controller is further configured to monitor at least one of: a pressure of the at least one vacuum pump; a temperature of the at least one vacuum pump; a current of the at least one vacuum pump; and an operating frequency of the at least one vacuum pump. For instance, the pressure and temperature may be monitored and controlled at a vacuum pump level, with voltage / current / frequency being monitored and controlled at a component level within the vacuum pump system. This tends to allow the vacuum pumps within the vacuum pump system to be controlled to meet various requirements of a given application, and to meet various tolerances of the vacuum pump equipment itself.

[0023] In some embodiments, each converter of the at least one vacuum pump comprises: a rectifier for converting an input AC power from an AC power supply, to a DC power; an inverter for converting the DC power to an output AC power, for driving the respective motor; and a DC link connected between the rectifier and inverter, for receiving the DC power from the rectifier and providing the DC power to the inverter. The rectifiers and inverters may comprise semiconductor devices and filters, for instance. Each of the rectifiers, inverters and DC links may have separate terminals to interface with controllers, control circuits and other electronics that may monitor and control their status.

[0024] By providing each converter with a rectifier and inverter connected by a respective DC link, tends to ensure greater redundancy is built into the vacuum pump system. Put differently, a common point of failure such as a common DC link, or common rectifier, for instance, is mitigated.

[0025] In some embodiments, the at least one vacuum pump system comprises a plurality of vacuum pumps. The plurality of vacuum pumps may comprise greater than two vacuum pumps.

[0026] Some embodiments comprise an electrical interconnection arranged to electrically connect the converters together, such that the converters can provide and / or receive regenerated energy to and / or from the electrical interconnection. In some embodiments the electrical interconnection electrically connects the DC links of the converters together. The electrical interconnection may be insulated conductive bars, wires or cables. The electrical interconnection may be a bus, i.e. , a DC electrical bus to which the DC links of the various converters can connect. This tends to allow for power sharing and regenerated energy sharing not only between two converters of two vacuum pumps, but for three, four, five or more converters and vacuum pumps. Expressed generally, the interconnection provides a scalable solution for more efficient use of regenerated energy across vacuum pump systems comprising plural vacuum pumps. Furthermore, the energy storage means may be electrically connected to the electrical interconnection.

[0027] In preferred embodiments, each converter of the plurality of vacuum pumps are connected to the electrical interconnection via an intermediate electrical protection means.

[0028] By providing an intermediate electrical protection means, the connections between converters via the electrical interconnection are protected by safety device components such that any transient events (i.e., inrush currents) experienced by one converter would not propagate and result in damage of other converters, allowing normal operation of the vacuum pump system. By way of example, if two converters are arranged to share regenerated energy between them, a transient event (such as a spike in current) could propagate from one converter to the other via the electrical interconnection, potentially damaging either or both converters (if, for instance, either is not specified for such current spikes). Intermediate electrical protection means can mitigate such an issue from arising. The electrical protection is based on the energy / power / voltage / current being shared between converters via the electrical interconnection, not on the drive voltages or current or power going to a particular pump motor. The intermediate electrical protection means accordingly supports scalability of the architecture for power sharing in a vacuum pump system.

[0029] In some embodiments, the intermediate electrical protection means comprises at least one of: a fuse; and a surge protector. There tends to be no separate control unit required for operation of these forms of intermediate electrical protection means.

[0030] Some embodiments comprise a first vacuum pump comprising: a first rotor; a first motor configured to drive the first rotor; a first converter configured to supply electrical power to the first motor to accelerate and decelerate the first rotor; and a second vacuum pump comprising: a second rotor; a second motor configured to drive the second rotor; a second converter configured to supply electrical power to the second motor to accelerate and decelerate the second rotor; wherein the second converter is electrically connected to the first converter via an electrical interconnection; wherein the first and / or second converter are further configured to: provide the regenerated energy from the first converter to the second converter during a deceleration of the first rotor, such that the regenerated energy can be used to accelerate the second rotor; and / or provide the regenerated energy from the second converter to the first converter during a deceleration of the second rotor, such that the regenerated energy can be used to accelerate the first rotor.

[0031] By providing the first and second vacuum pumps wherein the respective converters are interconnected, regenerated energy can be shared (for instance instantaneously) between the first and second vacuum pumps. The interconnection may be a conductive wire, wires, or cable attached to the first converter at a first end and attached to the second converter at a second end opposite the first end. The interconnection may be made between respective DC links of the first and second converters.

[0032] Some embodiments further comprise a third vacuum pump comprising: : a third rotor; a third motor configured to drive the third rotor; a third converter configured to supply electrical power to the third motor to accelerate and decelerate the third rotor; wherein the third converter is electrically connected to the first converter and the second converter via the electrical interconnection; wherein the first and / or second converter and / or third converter are further configured to: provide the regenerated energy from any of first converter, second converter, third converter, to another of the first converter, second converter and third converter, during a deceleration of the respective first rotor, second rotor or third rotor, such that the regenerated energy can be used to accelerate another of the first rotor, second rotor or third rotor.

[0033] Some embodiments further comprise an energy storage means electrically connected to the electrical interconnection.

[0034] It will be appreciated that the electrical interconnection allows for a scalable solution allows additional vacuum pumps and energy storage means to be added to the vacuum pump system. According to a further aspect of the invention, there is provided a method of energy regeneration in a vacuum pump system, comprising: decelerating a rotor of at least a first vacuum pump of the vacuum pump system, wherein the at least a first vacuum pump comprises the rotor, a motor configured to drive the rotor, and a converter configured to supply electrical power to the motor to accelerate and decelerate the rotor; operating the motor, using the converter, in a generator or braking mode for the deceleration of the rotor; and capturing as a regenerated energy, using the converter, at least a portion of the kinetic energy of the rotor during the deceleration.

[0035] The method may be a computer implemented method. The method may be embodied as a computer program i.e. , computer-readable instructions. Such a computer program may be provided on a non-transitory computer-readable storage medium, for instance. Such a non-transitory computer-readable storage medium may be implemented as memory in a controller, said controller also comprising at least one processor for executing the instructions stored in the memory, and thereby operating the methods disclosed herein.

[0036] Some embodiments further comprise capturing the regenerated energy in an energy storage means. The energy storage means may preferably comprise at least one of: a capacitor bank; a battery; and a flywheel.

[0037] Some embodiments comprise monitoring at least one of: a pressure of the at least one vacuum pump; a temperature of the at least one vacuum pump; a current of the at least one vacuum pump; and an operating frequency of the at least one vacuum pump.

[0038] The vacuum pump system may comprise a first vacuum pump comprising: a first rotor; a first motor configured to drive the first rotor; a first converter configured to supply electrical power to the first motor to accelerate and decelerate the first rotor; and a second vacuum pump comprising: a second rotor; a second motor configured to drive the second rotor; a second converter configured to supply electrical power to the second motor to accelerate and decelerate the second rotor; wherein the second converter is electrically connected to the first converter via an electrical interconnection. The method may further comprise, providing the regenerated energy from the first converter to the second converter during a deceleration of the first rotor via the electrical interconnection, such that the regenerated energy can be used to accelerate the second rotor; and / or providing the regenerated energy from the second converter to the first converter via the electrical interconnection during a deceleration of the second rotor, such that the regenerated energy can be used to accelerate the first rotor.

[0039] The vacuum pump system may further comprise a third vacuum pump comprising: a third rotor; a third motor configured to drive the third rotor; a third converter configured to supply electrical power to the third motor to accelerate and decelerate the third rotor; wherein the third converter is electrically connected to the first converter and the second converter via the electrical interconnection. The method may further comprise providing the regenerated energy from any of first converter, second converter, third converter, to another of the first converter, second converter and third converter, via the electrical interconnection, during a deceleration of the respective first rotor, second rotor or third rotor, such that the regenerated energy can be used to accelerate another of the first rotor, second rotor or third rotor.

[0040] Some embodiments comprise adaptively decelerating or braking the rotor, when in the generator or braking mode, over a required time period based on an available power.

[0041] It will be appreciated that particular features of different aspects of the invention tend to share the technical effects and benefits of corresponding features of other aspects of the invention. More specifically, the methods described herein share the same technical benefits as the vacuum pump system described herein.

[0042] It will also be appreciated that the use of the terms “first” and “second”, and the like, are merely intended to help distinguish between similar features and are not intended to indicate a relative importance of one feature over another, unless otherwise specified. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0044] Figure 1 shows a schematic illustration of a prior art vacuum pump system;

[0045] Figure 2 shows a schematic illustration of a vacuum pump system;

[0046] Figure 3 shows a further schematic illustration of a vacuum pump system;

[0047] Figure 4 shows a flowchart of a method of energy regeneration; and

[0048] Figure 5 shows an embodiment of a controller.

[0049] DETAILED DESCRIPTION

[0050] Figure 1 shows a schematic illustration of a prior art vacuum pump system 100.

[0051] A common inlet 110 is shown for receiving process gases. The inlet 110 is connected to a plurality of vacuum pumps 120, 130, 140, 150, 160. The plurality of vacuum pumps 120, 130, 140, 150, 160 are also connected to a common outlet or exhaust 170.

[0052] Three of the vacuum pumps 120, 130, 140 are primary pumps. Pumps 120, 130, 140 work against atmospheric pressure or a similar high pressure into the exhaust pipe 170. The rotating mechanical element (not visible) of pumps 120, 130, 140 comprise intermeshed dry screw rotors, offering a high internal compression and energy-efficient operation.

[0053] Two of the vacuum pumps 150, 160, are secondary pumps. Pumps 150, 160 extend the range of application of the primary pumps 120, 130, 140 to lower ultimate pressures. The rotating mechanical element (not visible) of pumps 150, 160 comprise roots rotors that cannot, of themselves, compress to atmosphere and hence require the corresponding primary pumps 120, 130, 140. A three-phase AC power from an AC grid 180 is shown as feeding each of the pumps 120, 130, 140, 150, 160. The use of the three-phase AC power by the pumps 120, 130, 140, 150, 160, will now be described, using the example of primary pump 120.

[0054] The primary pump 120 is shown as comprising a rotating mechanical element / rotor 121 , an electric motor 122 configured to drive the rotor 121 , and a converter 123 configured to supply electrical power to the motor 122 to accelerate and decelerate the rotor 121 .

[0055] The converter 123 comprises a rectifier, a DC link / bus and an output converter (not visible). The rectifier is an input rectifier bridge comprising a plurality of semiconductor devices and filters that convert the three-phase AC power from the AC grid 180 to a DC power. The DC power is provided to the DC link / DC bus, which is then input, via the DC link / bus, to the inverter. The inverter also comprises a plurality of semiconductor devices and filters that convert the DC power to an output AC power of the required voltage / current / frequency for the motor 122.

[0056] The operation of the vacuum pump system 100 begins with a ramping up of the primary pumps 120, 130, 140. By way of example, this involves the converter 123 providing power to the motor 122 to accelerate the rotor 121 to the required rotational frequency and operating the pump 120 until the desired pressure is reached. Once the primary pumps 120, 130, 140 have reached their operating pressure, the secondary pumps 150, 160 are ramped up to reach the overall ultimate pressure for the vacuum pump system 100.

[0057] Under certain conditions, such as during a load lock or for a process necessitating varying pressure demands, the pumps 120, 130, 140, 150, 160, or any combination thereof, may require ramping up (accelerating of the respective rotors) or ramping down (decelerating of the respective rotors) during operation. This is controlled by the respective converters (i.e., converter 123) of the pumps 120, 130, 140, 150, 160. During deceleration, excess kinetic energy is lost as dissipated heat. For example, the rotor 121 presents a high inertia rotating mechanical element having substantial kinetic energy. When the rotor 121 is decelerated by ‘braking’ or operating the motor 122 as a generator, the kinetic energy of rotor 121 is dissipated as heat. This presents an inefficient operation of the pump 120 through a wasting of the kinetic energy.

[0058] Figure 2 shows a schematic illustration of a vacuum pump system 200 that is in accordance with aspects of the present disclosure. The vacuum pump system 200 may be considered as analogous to the vacuum pump system 100 of Figure 1 , unless otherwise discussed below. In this regard, the inlet 210 and exhaust 270 are analogous to the inlet 110 and outlet 170; the pumps 220, 230, 240, 250, 260 are analogous to the pumps 120, 130, 140, 150, 160; the AC grid 280 is analogous to grid 180; and the rotor 221 , motor 222, and converter 223 are analogous to the rotor 121 , motor 122 and converter 123.

[0059] During a defined operational cycle, there is sufficient kinetic energy present in the rotating high inertia mechanical elements of the pumps 220, 230, 240, 250, 260 (i.e., rotor 221 , for instance) during the ramp down period of the pumps 220, 230, 240, 250, 260, such that utilisation of the kinetic energy can be considered. In accordance with the disclosure herein, the converters (for instance 223) can be used to operate their respective motors (i.e., motor 222) in a generator or braking mode for a deceleration of the respective rotor (i.e., rotor 221). The converters (i.e., converter 223) can be used to capture as a regenerated energy at least a portion of the kinetic energy of the rotor (i.e., rotor 221) during the deceleration. Hence the kinetic energy can be converted and used. For the vacuum pump 220, the control algorithm for the converter 223 is adapted to allow the motor 222 to act as a generator. A controller (for instance the controller 500 of Figure 5 described below), effects such a braking and capturing of regenerated energy. The controller may comprise a memory and at least one processor coupled with the memory, with the memory comprising instructions to executes the control algorithms disclosed herein. With regard to vacuum pump 220, the controller is further configured to adaptively decelerate or brake the rotor 221 when in the generator or braking mode over a required time period based on an available power. The required power may be the instantaneous power required to accelerate another pump 230, 240, 250, 260 in the vacuum pump system 200, for instance. The vacuum pump system 200 further augments the system 100 of Figure 1 by providing each converter of the plurality of vacuum pumps 200, 230, 240, 250, 260 with its own electronic protection means.

[0060] The vacuum pump system 200 further augments the system 100 of Figure 1 by providing each converter of the plurality of vacuum pumps 220, 230, 240, 250, 260 with an interconnection via an intermediate electrical protection means. The intermediate electrical protection means is a fuse. By way of example, a vacuum pump 230 and vacuum pump 260 are shown with an electrical interconnection 290 and intermediate electrical protection means 295 therebetween.

[0061] More specifically, vacuum pump 230 may be considered as a first vacuum pump 230 comprising a first rotor 231 ; a first motor 232 configured to drive the first rotor 231 ; and a first converter 233 configured to supply electrical power to the first motor 232 to accelerate and decelerate the first rotor 231 . The vacuum pump 260 may be considered a second vacuum pump 260 comprising: a second rotor 261 ; a second motor 262 configured to drive the second rotor 261 ; and a second converter 263 configured to supply electrical power to the second motor 262 to accelerate and decelerate the second rotor 261. As shown, the second converter 263 is electrically connected to the first converter 233 using the electrical interconnection 290 and intermediate electrical protection means 295. A controller (not visible) is configured to first and / or second converter 233, 263 to provide the regenerated energy from the first converter 233 to the second converter 263 during a deceleration of the first rotor 231 , such that the regenerated energy can be used to accelerate the second rotor 261 ; and / or to provide the regenerated energy from the second converter 263 to the first converter 233 during a deceleration of the second rotor 261 , such that the regenerated energy can be used to accelerate the first rotor 231 . Hence, the kinetic energy of the first and / or second rotors 231 , 261 , whilst initially converted to electrical energy, can then substantially instantaneously be used in the other pump (i.e., pump 260, 230). Furthermore, the electrical interconnection 290 and intermediate electrical protection means 295 provides protection from transients (such as current spikes) propagating from one pump to the other pump, mitigating the risk of damage and providing redundancy to the operation of the vacuum pump system 200.

[0062] To aid the understanding of aspects of the present disclosure, a discussion of the operation of a converter 223, 233, 263, will now be made with reference to the generator or braking mode. Whilst the discussion may refer to the exchange of regenerated energy between two converters, it will be appreciated that the electrical interconnection 290 provides a scalable solution. Expressed differently, any of vacuum pumps 220, 230, 240, 250, 260 may share regenerated energy with each other owing to the presence of the electrical interconnection 290 providing an electrical bus to which each converter of vacuum pumps 220, 230, 240, 250, 260 is connected.

[0063] To achieve a reduction in rotational frequency of a rotor 221 , 231 , 261 , braking is applied to the motor 222, 232, 262 to reduce the speed of the rotor

[0064] 221 , 231 , 261 . This braking is performed by the motor 222, 232, 262 operating in a generator mode in which the motor 222, 232, 262 converts the mechanical kinetic energy of rotor 221 , 231 , 261 into electrical energy. In effect, the motor

[0065] 222, 232, 262 generates AC power when performing the braking action. The generated AC power is then transferred to the respective converter 223, 233, 263 via an electrical coupling electrically connecting the converter 223, 233, 263 to the respective motor 222, 232, 262. The generator AC power is converted into DC power by the converter 223, 233, 263. The regenerated DC power may then be provided to another converter 223, 233, 263, through the electrical interconnection 290. The another converter 223, 233, 263 may then convert the received regenerated DC power to an AC power for use in driving the respective motor 222, 232, 262. Hence, the regenerated energy can be used to drive another vacuum pump, reducing or eliminating the power taken from the grid 280. As will be appreciated, the converters 223, 233, 263 effectively operate in reverse when operating in the braking or generator mode. More specifically, the inverter (not visible) of a given converter 223, 233, 263 becomes a rectifier.

[0066] Figure 3 shows a further schematic illustration of a vacuum pump system

[0067] 300. The vacuum pump system 300 comprises all of the features and functionality of the vacuum pump system 200 of Figure 2. Hence, like reference numerals refer to like features across the systems 200, 300.

[0068] However, the vacuum pump system 300 further comprises energy storage means 398. The energy storage means 398 is a bank of capacitors and is shown as being connected to the various electrical interconnections 390 between the converters (i.e., between converter 333 and 363). In the system 300, a controller (for instance the controller 500 of Figure 5 described below) causes the converters of the vacuum pumps (i.e., converter 333 or 363) to capture the regenerated energy in the energy storage means 398. Hence the regenerated energy can be stored for later use i.e., for driving one of the vacuum pumps 320, 330, 340, 350, 360. Indeed, any of vacuum pumps 320, 330, 340, 350, 360 may store and use regenerated energy in / from the energy storage means 398 owing to the connection of the energy storage means 398 to the electrical interconnection 390 which itself acts as an electrical bus connecting the converters of the vacuum pumps 330, 340, 350, 360.

[0069] Figure 4 shows a flowchart of a method 400 of energy regeneration.

[0070] A first step 410 comprises decelerating a rotor of at least a first vacuum pump of the vacuum pump system, wherein the at least a first vacuum pump comprises the rotor, a motor configured to drive the rotor, and a converter configured to supply electrical power to the motor to accelerate and decelerate the rotor.

[0071] A further step 420 comprises operating the motor, using the converter, in a generator or braking mode for the deceleration of the rotor.

[0072] A further step 430 comprises capturing as a regenerated energy, using the converter, at least a portion of the kinetic energy of the rotor during the deceleration.

[0073] Figure 5 shows an embodiment of a controller 500 as may be used in the vacuum pump systems and methods disclosed herein. The controller 500 comprises a memory 510 coupled with at least one processor 520. The memory 510 comprises computer-readable instructions which when executed by the at least one processor 520, cause the controller 500 to execute the methods described herein. For instance the instructions may cause the controller 500 to execute the method 400. The controller 500 may control the converters of the vacuum pump apparatuses 200, 300. The controller 500 may be located within the converters or separate thereto.

[0074] An advantage of the embodiments described herein tends to be that kinetic energy of the rotors of vacuum pumps in vacuum pump systems, is not wasted when the rotors are decelerated.

[0075] A further advantage of the embodiments described herein tends to be that the kinetic energy is utilised. In this manner, the overall energy used by the vacuum pump system can be reduced.

[0076] A further advantage of the embodiments described herein tends to be that the kinetic energy is converted to another useful form (i.e. , electrical energy that is instantaneously used or stored for later use, or mechanical energy in a flywheel).

[0077] A further advantage of the embodiments described herein tends to be that overloading of the converters of vacuum pumps is avoided during braking, through the redistribution, use or storage of excess kinetic energy into other forms of useful energy.

[0078] A further advantage of the embodiments described herein tends to be that redundancy is in-built into the vacuum pump system architecture.

[0079] A further advantage of the embodiments described herein tends to be that the vacuum pumps within a vacuum pump system can be operated either as standalone units or with external controllers interfacing with the converters of the pumps.

[0080] A further advantage of the embodiments described herein tends to be that vacuum pumps in the vacuum pump system are adaptively monitored and ramp down times are selected to optimise regenerated power for a given requirement.

[0081] Whilst specific embodiments described herein refer to the term ‘converter’ it will be appreciated that this is a term may include ‘frequency converter’. It will be appreciated that for a vacuum pump system comprising N pumps, the disclosure herein may be applicable to N-1 pumps in the vacuum pump system. More specifically, the use of an electrical interconnection or electrical bus to which the converters connect tends to allow for scalability to vacuum pump systems comprising greater than two vacuum pumps.

[0082] Whilst specific embodiments described herein refer to a controller being used to perform the control of the converters, other embodiments may not use a controller and rely on the converters themselves to control the motor without additional control signals from a separate controller.

[0083] Whilst the embodiments disclosed herein may refer to specific numbers or types of pumps, this is not intended to be limiting. It will be appreciated that the disclosure herein can be extended to other types of quantities of pumps in a vacuum pump system.

[0084] Whilst the embodiments described herein show power being received from an AC grid supply, other sources of AC power can be envisaged i.e. , a generator.

[0085] Reference numeral list

[0086] 100 vacuum pump system

[0087] 110 inlet

[0088] 120 vacuum pump

[0089] 121 rotor

[0090] 122 motor

[0091] 123 converter

[0092] 130 vacuum pump

[0093] 140 vacuum pump

[0094] 150 vacuum pump

[0095] 160 vacuum pump

[0096] 170 outlet / exhaust

[0097] 180 AC grid / supply

[0098] 200 vacuum pump system

[0099] 210 inlet

[0100] 220 vacuum pump

[0101] 221 rotor

[0102] 222 motor

[0103] 223 converter

[0104] 230 vacuum pump

[0105] 231 rotor

[0106] 232 motor

[0107] 233 converter

[0108] 240 vacuum pump

[0109] 250 vacuum pump

[0110] 260 vacuum pump 261 rotor

[0111] 262 motor

[0112] 263 converter

[0113] 270 outlet / exhaust

[0114] 280 AC grid / supply

[0115] 290 electrical interconnection

[0116] 295 intermediate electrical protection means

[0117] 300 vacuum pump system

[0118] 310 inlet

[0119] 320 vacuum pump

[0120] 321 rotor

[0121] 322 motor

[0122] 323 converter

[0123] 330 vacuum pump

[0124] 331 rotor

[0125] 332 motor

[0126] 333 converter

[0127] 340 vacuum pump

[0128] 350 vacuum pump

[0129] 360 vacuum pump

[0130] 361 rotor

[0131] 362 motor

[0132] 363 converter

[0133] 370 outlet / exhaust

[0134] 380 AC grid / supply

[0135] 390 interconnection 395 intermediate electrical protection means

[0136] 398 energy storage means

[0137] 400 method

[0138] 410 first step of method

[0139] 420 further step of method

[0140] 430 further step of method

[0141] 500 controller

[0142] 510 memory

[0143] 520 at least one processor

Claims

CLAIMS1 . A vacuum pump system, comprising: at least one vacuum pump each comprising: a rotor; a motor configured to drive the rotor; a converter configured to supply electrical power to the motor to accelerate and decelerate the rotor; wherein each converter is configured to: operate the motor in a generator or braking mode for a deceleration of the rotor; and capture as a regenerated energy at least a portion of the kinetic energy of the rotor during the deceleration.

2. The vacuum pump system of claim 1 , further comprising a controller configured to cause each converter of the vacuum pump system to: operate the motor in the generator or braking mode for the deceleration of the rotor; and capture as the regenerated energy the at least a portion of the kinetic energy of the rotor during the deceleration.

3. The vacuum pump system of claim 2, wherein the controller is configured with each converter to adaptively operate the motor in the generator or braking mode and capture the regenerated energy.

4. The vacuum pump system of any preceding claim, further comprising energy storage means, wherein each converter is further configured to capture the regenerated energy in the energy storage means.

5. The vacuum pump system of claim 4, wherein the energy storage means comprises at least one of: a capacitor bank; a battery; and a flywheel.

6. The vacuum pump system of any preceding claim, wherein each converter of the at least one vacuum pump, comprises an electronic protection means.

7. The vacuum pump system of claim 6, wherein the electronic protection means is configured to provide at least one of: an under / over voltage protection for the respective vacuum pump; an over current protection for the respective vacuum pump; and an over temperature protection for the respective vacuum pump.

8. The vacuum pump system of any one of claims 2-7 when dependent on claim 2, wherein the controller is further configured to monitor at least one of: a pressure of the at least one vacuum pump; a temperature of the at least one vacuum pump; a current of the at least one vacuum pump; and an operating frequency of the at least one vacuum pump.

9. The vacuum pump system of any preceding claim, wherein each converter of the at least one vacuum pump comprises: a rectifier for converting an input AC power from an AC power supply, to a DC power;an inverter for converting the DC power to an output AC power, for driving the respective motor; and a DC link connected between the rectifier and inverter, for receiving the DC power from the rectifier and providing the DC power to the inverter.

10. The vacuum pump system of any preceding claim, wherein the at least one vacuum pump comprises a plurality of vacuum pumps.

11. The vacuum pump system of claim 10, wherein the plurality of vacuum pumps comprises greater than two vacuum pumps.

12. The vacuum pump system of any one of claims 10-11 , comprising an electrical interconnection arranged to electrically connect the converters of the plurality of vacuum pumps together, such that the converters can provide and / or receive regenerated energy to and / or from the electrical interconnection.

13. The vacuum pump system of claim 12 when dependent upon claim 9, wherein the electrical interconnection electrically connects the DC links of the converters together.

14. The vacuum pump system of any one of claims 12-13, wherein each converter of the plurality of vacuum pumps is connected to the electrical interconnection via an intermediate electrical protection means.

15. A method of energy regeneration in a vacuum pump system, comprising: decelerating a rotor of at least a first vacuum pump of the vacuum pump system, wherein the at least a first vacuum pump comprises the rotor, a motor configured to drive the rotor, and a converter configured to supply electrical power to the motor to accelerate and decelerate the rotor;operating the motor, using the converter, in a generator or braking mode for the deceleration of the rotor; and capturing as a regenerated energy, using the converter, at least a portion of the kinetic energy of the rotor during the deceleration.

Images