CONVEYANCE SYSTEM WITH REGENERATIVE DRIVE

Abstract

A conveyance system includes an alternating current (AC) power source (28), a machine (30) for moving a conveyance apparatus, and a regenerative drive (20). The machine is connected to the AC power source by the regenerative drive. The regenerative drive includes a direct current (DC) bus (26), a converter (22) and a machine control circuit (24). The conveyance system further includes an energy harvesting device (32) and a switching arrangement (34). The switching arrangement (34) is arranged between the energy harvesting device (32) and the machine control circuit (24), and is switchable between a first condition, in which the energy harvesting device (32) is disconnected from the machine control circuit (24), and a second condition in which the energy harvesting device (32) is operatively connected to at least one switching device of the second plurality of switching devices (23) of the machine control circuit (24).

Claims

1. A conveyance system (1, 1), comprising: an alternating current (AC) power source (28, 28, 28, 28, 280); a machine (30, 30, 30, 30, 300) for moving a conveyance apparatus (2, 2); a regenerative drive (20, 20, 20, 20, 200), wherein the machine (30, 30, 30, 30, 300) is connected to the AC power source (28, 28, 28, 28, 280) by the regenerative drive (20, 20, 20, 20, 200), the regenerative drive (20, 20, 20, 20, 280) comprising: a direct current (DC) bus (26, 26, 26, 26, 260); a converter (22, 22, 22, 22, 220), comprising a first plurality of switching devices (21, 21, 21, 21, 210) in selective communication with each phase of the AC power source (28, 28, 28, 28, 280) and with the DC bus (26, 26, 26, 26, 260); and a machine control circuit (24, 24, 24, 24, 240), comprising a second plurality of switching devices (23, 23, 23, 23, 230) in selective communication with each phase of the machine (30, 30, 30, 30, 300) and with the DC bus (26, 26, 26, 26, 260); the conveyance system further comprising: an energy harvesting device (32, 32, 32, 32, 320); and a switching arrangement (34, 340, 34a, 34b, 34c, 340, 340), arranged between the energy harvesting device (32, 32, 32, 32, 320) and the machine control circuit (24, 24, 24, 24, 240), wherein the switching arrangement (34, 340, 34a, 34b, 34c, 340, 340) is switchable between a first condition, in which the energy harvesting device (32, 32, 32, 32, 320) is disconnected from the machine control circuit (24, 24, 24, 24, 240), and a second condition in which the energy harvesting device (32, 32, 32, 32, 320) is operatively connected to at least one switching device of the second plurality of switching devices (23, 23, 23, 23, 230) of the machine control circuit (24, 24, 24, 24, 240).

2. The conveyance system (1, 1) of claim 1, further comprising a switching controller (40, 40, 40, 40, 400), arranged to control the switching arrangement (34, 340, 34a, 34b, 34c, 340, 340) to switch between the first condition and the second condition.

3. The conveyance system (1, 1) of claim 2, wherein the switching controller (40, 40, 40, 40, 400) is arranged to switch the switching arrangement (34, 340, 34a, 34b, 34c, 340, 340) to the second condition when the machine (30, 30, 30, 30, 300) is stationary.

4. The conveyance system (1, 1) of claim 2, comprising a drive controller (41, 410) arranged to control switching of the first plurality of switching devices (21, 210) and the second plurality of switching devices (23, 230) so as to control the machine (30, 300), wherein the drive controller (41, 410) comprises the switching controller (40, 400).

5. The conveyance system (1, 1) of claim 1, wherein the machine (30) comprises a star point (31), at which all phases of the machine (30) meet, wherein the star point (31) is arranged to be accessible from an exterior of the machine (30), and wherein the switching arrangement (34) is connected to the star point (31).

6. The conveyance system (1, 1) of claim 1, wherein the switching arrangement (340, 34a, 34b, 34c) is connected between one phase of the machine control circuit (24, 24, 24, 24, 240) and the energy harvesting device (32, 32, 32, 320).

7. The conveyance system (1, 1) of claim 6, further comprising an inductor (38, 38a, 38b, 38c, 380), connected in series with the switching arrangement (340, 34a, 34b, 34c, 340).

8. The conveyance system (1, 1) of claim 6, wherein the machine control circuit is an inverter (24), and further comprising a second switching arrangement (34a, 34b, 34c), wherein the second switching arrangement (34a, 34b, 34c) is connected between a second phase of the inverter (24) and the energy harvesting device (32).

9. The conveyance system (1, 1) of claim 6, wherein the conveyance system (1, 1) further comprises at least one machine switch (37, 370), arranged to selectively connect a different phase of the machine control circuit (24, 24, 24, 24) with a phase of the machine (30, 30, 30).

10. The conveyance system (1, 1) of claim 1, further comprising a voltage measurement device (44), connected to the energy harvesting device (32) and arranged to measure the voltage produced by the energy harvesting device (32).

11. The conveyance system (1, 1) of claim 1, wherein the conveyance system (1, 1) is an elevator system.

12. A building (100), comprising the conveyance system (1, 1) of claim 1, wherein the building (100) is a residential building, or an office building, or a commercial building.

13. A method of operating a regenerative drive (20, 20, 20, 20, 200) of a conveyance system (1, 1), the regenerative drive (20, 20, 20, 20, 200) comprising a direct current (DC) bus (26, 26, 26, 26, 260), a converter (22, 22, 22, 22, 220) comprising a first plurality of switching devices (21, 21, 21, 21, 210) in selective communication with each phase of an AC power source (28, 28, 28, 28, 280) and with the DC bus (26, 26, 26, 26, 260), and a machine control circuit (24, 24, 24, 24, 240) comprising a second plurality of switching devices (23, 23, 23, 23, 230) in selective communication with each phase of a machine (30, 30, 30, 30, 300) and with the DC bus (26, 26, 26, 26, 260), the method comprising: driving movement of the machine (30, 30, 30, 30, 300) with power from the AC power source (28, 28, 28) using the regenerative drive (20, 20, 20, 20, 200), wherein the machine (30, 30, 30, 30, 300) is arranged to move a conveyance apparatus (2, 2) of the conveyance system (1, 1); when motion of the machine (30, 30, 30, 30, 300) is being braked, harvesting power from the machine (30, 30, 30, 30, 300) using the regenerative drive (20, 20, 20, 20, 200); switching a switching arrangement (34, 340, 34a, 34b, 34c, 340, 340) from a first condition, in which an energy harvesting device (32, 32, 32, 32, 300) is disconnected from the machine control circuit (24, 24, 24, 24, 240) of the regenerative drive (20, 20, 20, 20, 200), to a second condition in which the energy harvesting device (32, 32, 32, 32, 320) is operatively connected to at least one switching device of the second plurality of switching devices (23, 23, 23, 23, 230) of the machine control circuit (24, 24, 24, 24, 240).

14. The method of claim 13, further comprising: transferring power harvested from the energy harvesting device (32, 32, 32, 32, 320) when the machine (30, 30, 30, 30, 300) is stationary to the AC power source (28, 28, 28, 28, 280), through the converter (22, 22, 22, 22, 220); and/or transferring power harvested from the energy harvesting device (32, 32, 32, 32, 320) when the machine (30, 30, 30, 30, 300) is stationary to a battery (36, 36, 36) connected to the DC bus (26, 26, 26, 26, 260).

15. A software product which, when implemented on a controller (40, 40, 40, 40, 400) of a conveyance system (1, 1), causes the controller (40, 40, 40, 40, 400) to carry out the method as claimed in claim 13.

Description

DRAWING DESCRIPTION

[0040] Certain preferred examples of this disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0041] FIG. 1 is a schematic drawing showing a building containing a conveyance system according to a first example of a first aspect of the present disclosure;

[0042] FIG. 2 is a schematic drawing showing the regenerative drive of FIG. 1 and its associated components in greater detail;

[0043] FIG. 3 is a schematic drawing showing a conveyance system according to a second example of the first aspect of the present disclosure;

[0044] FIG. 4 is a schematic drawing showing the regenerative drive of FIG. 3 and its associated components in greater detail;

[0045] FIG. 5 is a schematic drawing showing a regenerative drive and its associated components according to a third example of a first aspect of the present disclosure;

[0046] FIG. 6 is a schematic drawing showing a regenerative drive and its associated components according to a fourth example of a first aspect of the present disclosure;

[0047] FIG. 7 is a schematic drawing showing a regenerative drive and its associated components according to a fifth example of a first aspect of the present disclosure; and

[0048] FIG. 8 is a flow diagram showing a method according to a second aspect of the present disclosure.

DETAILED DESCRIPTION

[0049] FIG. 1 is a schematic diagram showing a conveyance system 1 according to an example of the present disclosure. The conveyance system 1 is located within a building 100. In this particular example the conveyance system 1 is an elevator system. The conveyance system 1 includes a conveyance apparatus 2, which in this example is an elevator car configured to travel upwards and downwards in a hoistway 4, moved by tension members 6, which may be, for example, belts or ropes. The tension members 6 are moved by a machine 30, under the control of a regenerative drive 20, discussed in greater detail below with reference to FIG. 2. The regenerative drive 20 and the machine 30 are controlled by a drive controller 41, which receives signals from the main conveyance system controller 42. The signals from the main conveyance system controller 42 indicate how the conveyance system should be operated, e.g., they provide a car call to respond to. The regenerative drive 20 is operable as a machine drive and a regenerative drive capable of harvesting regenerative energy from the machine 30 during braking of a load being driven, which in this case is the conveyance apparatus 2.

[0050] The regenerative drive 20 receives power from a mains AC power source 28, through the wiring 10. It is then wired to the machine 30 by machine wiring 12. The regenerative drive 20 is also connected to an energy harvesting device 32 by wiring 14. In this example the energy harvesting device 32 is a solar panel, comprising a plurality of photovoltaic cells. The energy harvesting device 32 is connected to the machine 30 by wiring 16. The drive controller 41 is connected to both the regenerative drive 20, by wiring 15, and to the machine 30, by wiring 17. The drive controller 41 is also connected to switching arrangements 34, 35 via wiring 19. A first switching arrangement 34 is arranged between the machine 30 and the energy harvesting device 32. This arrangement is described in greater detail below with reference to FIG. 2.

[0051] FIG. 2 is a schematic diagram, showing the regenerative drive 20 of FIG. 1 and its associated components in greater detail for a first example. The AC power source 28 can be, for example, an electrical main line. In the example of FIG. 2 the regenerative drive system 20 is a regenerative drive that includes a converter 22 having 3 phase legs, R, S, and T. Each phase leg, R, S, and T, includes switching devices 21 controlled by control signals from a drive controller 41 (i.e., through wiring 15) to convert AC power to DC power on a DC bus 26 having a high side 27 and a low side 29. The regenerative drive system 20 also includes a machine control circuit, which in this example is an inverter 24 having 3 phase legs, W, V, and U. Each phase leg, W, V, and U, includes switching devices 23 controlled by control signals from the drive controller 41 to convert DC power across the DC bus 26 to AC drive signals to power the machine 30. By controlling the switching of the switching devices 21, 23 (and therefore the voltage supplied to the machine 30) the drive controller 41 controls operation of the machine 30, i.e., whether the machine is driven to rotate or not. The drive controller 41 can also control operation of a machine brake (not shown) (i.e., via wiring 17) connected to the machine 30, which can brake motion of the machine 30. The drive controller 41 may be implemented using a general-purpose microprocessor executing a computer program stored on a storage medium to perform the operations described herein. Alternatively, the drive controller 41 may be implemented in hardware (e.g., ASIC, FPGA) or in a combination of hardware/software.

[0052] The energy harvesting device 32 (in this example a solar panel) is selectively connectable to the inverter 24 by operation of the first switching arrangement 34 and the second switching arrangement 35. The second switching arrangement 35 is arranged between a negative pole of the energy harvesting device 32, and the low side 29 of the DC bus 26. The drive controller 41 in this example also provides a switching controller 40, that controls the first switching arrangement 34 and the second switching arrangement 35. In particular, the switching controller 40 sends signals to the switching arrangements 34, 35 (e.g., via wiring 19) to control the switching arrangements 34, 35 to switch between a first condition (as shown in FIG. 2), in which the energy harvesting device 32 is disconnected from the inverter 24, and a second condition (not shown) in which the energy harvesting device 32 is operatively connected to the inverter 24. In particular, the energy harvesting device 32 is connected to the inverter 24 via the machine 30, and in particular it is connected to the star point 31 of the winding. The star point 31 is the position at which all three windings of the machine 30 meet, and at which the current is therefore the sum of the current on the three windings.

[0053] As stated above, in this example, the switching controller 40 is provided by the drive controller 41. The drive controller 41 also controls operation of the machine 30 and the regenerative drive 20, as described above, and therefore it has knowledge of the planned movement of the machine 30. The switching controller 40 can therefore control the switching arrangements 34, 35 to connect the energy harvesting device 32 to the inverter 24 when the machine 30 is stationary, since when the machine 30 is stationary the inverter 24 of the regenerative drive 20 is not in use for either powering or receiving power from the machine 30. As described above, the switching controller 40 may control the switching arrangements 34, 35 to switch only when the time in the second condition will be (or is predicted to be) sufficiently long to make the switching process worthwhile.

[0054] When the energy harvesting device 32 is not connected to the inverter (i.e., when the switching arrangement 34 is in the first condition) there is no current flow from the energy harvesting device 32 and therefore no power generation. The energy harvesting device 32 will simply generate an open-circuit voltage at its output clamps.

[0055] When the switching arrangements 34, 35 are switched into the second (closed) condition, and the energy harvesting device 32 connected to the inverter 24, harvested power from the energy harvesting device 32 can be sent to the AC power source 28 (e.g., to the mains grid) through the converter 22, or alternatively can be sent to a battery 36, which is connected to the DC link 26. The machine 30 includes inductors 25 connected on each phase of the machine 30. These act to control the current as current flows back from the energy harvesting device 32 to the DC link 26. Supplying the power back to the DC link 26 in this way also enables it to then easily be passed through the converter 22 to be returned to the AC power source 28, if required.

[0056] FIG. 3 shows a conveyance apparatus 1 according to a second example of the present disclosure, and FIG. 4 shows certain components of that conveyance apparatus 1 in greater detail. This example is largely very similar to that of FIGS. 1 and 2. Like components are labelled with the same reference numeral, but followed by an apostrophe ', and will not be described in detail again. Only those components differing from the example of FIGS. 1 and 2 will be described in detail.

[0057] In this second example, the main conveyance system controller 42 provides the drive controller 41 that controls the regenerative drive 20 and the machine 30. A separate switching controller 40 controls the switching arrangements 340, 350, which are described in greater detail with reference to FIG. 4.

[0058] In contrast to the first example, in which the energy harvesting device is connected to the star point of the machine, in this second example, the energy harvesting device 32 is connected to the W phase of the inverter 24 (although it will be understood that any of the three phases W, V, U could be used). The switching arrangements 340, 350, under the control of switching controller 40, controls whether the energy harvesting device 32 is connected to the inverter 24, or disconnected, based on the condition of the switching arrangements 340, 350 (i.e., whether they are open or closed). The first switching arrangement 340 is located between the energy harvesting device 32 (specifically its positive pole) and the phase of the inverter 24 (i.e., in series between them). The second switching arrangement 350 is connected between the negative pole of the energy harvesting device 32 and the low side of the DC bus 26. Also connected in series with the first switching arrangement is an inductor 38 and a voltage measurement device 44. Measuring the voltage produced by the energy harvesting device 32 using the voltage measurement device 44 allows maximum power point tracking to be used in order to harvest the maximum available power from the energy harvesting device 32.

[0059] The inductor 38 helps control the flow of current from the energy harvesting device. In some examples, particularly where a very large current is drawn from the energy harvesting device 32, it may be preferable that the energy harvesting device 32 is connected to more than one phase of the inverter 24, or even to every phase of the inverter 24. Such an arrangement is illustrated in the third example, shown in FIG. 5. Many components are alike with those shown in FIG. 4, and will not be described in detail again. Like components are labelled with like reference numbers but followed by an additional apostrophe, compared to those used for the second example of FIGS. 3 and 4 (and therefore by two apostrophes compared to those used for the first example of FIGS. 1 and 2).

[0060] In this third example, instead of only one switching arrangement and inductor, as shown in FIG. 4, there is now one such arrangement for each phase of the inverter 24. Thus, the conveyance system includes a first switching arrangement 34a, connected between one phase of the inverter 24 (W) and the energy harvesting device 32. A first inductor 38a is connected between the switching arrangement 34a and the energy harvesting device 32, i.e., in series with them. The conveyance system further includes a second switching arrangement 34b, connected between one phase of the inverter 24 (V) and the energy harvesting device 32. A second inductor 38b is connected between the switching arrangement 34b and the energy harvesting device 32. The conveyance system also includes a third switching arrangement 34c, connected between one phase of the inverter 24 (U) and the energy harvesting device 32. A third inductor 38c is connected between the switching arrangement 34c and the energy harvesting device 32. A fourth switching arrangement 350 is connected between the negative pole of the energy harvesting device 32 and the low side of the DC bus 26.

[0061] FIG. 6 shows a fourth example. It is similar to that of FIGS. 4 and 5, since the positive pole of the energy harvesting device 32 is connected directly to a phase (W) of the inverter 24, but in this arrangement no additional inductors are needed. Many components are alike with those shown in the preceding Figures, and will not be described in detail again. Like components are labelled with like reference numbers but followed by an additional apostrophe, compared to those used for the third example of FIG. 5 (and therefore by two apostrophes compared to the second example of FIGS. 3 and 4 and by three apostrophes compared to those used for the first example of FIGS. 1 and 2).

[0062] In this example, the machine switches 37 connecting the three phases of the machine 30 to the three phases of the inverter 24 are individually switchable (which is not standard in such an arrangement). As a result, the switch on one of the phases V, U that the switching arrangement 340 is not connected to can be closed when the switching arrangements 340, 350 are closed. This causes two of the inductors of the machine 30 to be connected in series with the energy harvesting device 32. In this arrangement the inverter phase connected to the closed switch of the machine switches 37 (i.e., phase V or U), will be the only actively switching phase. This arrangement therefore allows the existing inductors of the machine 30 to be re-used during energy harvesting, so that additional inductors are not required.

[0063] FIG. 7 is a schematic diagram, showing a regenerative drive 200 and its associated components according to a fifth example of a first aspect of the present disclosure.

[0064] The regenerative drive 200 includes a converter 220 having 3 phase legs, R, S, and T. Each phase leg, R, S, and T, includes switching devices 210 controlled by control signals from a drive controller 410 to convert AC power supplied by an AC power source 280 to DC power on a DC bus 260 having a high side 270 and a low side 290. The AC power source 280 can be, for example, an electrical main line.

[0065] The regenerative drive system 200 also includes a machine control circuit, which in this example is a DC drive 240. The DC drive 240 includes a plurality of switching devices 230, that are arranged to alter the voltage supplied on the DC bus 260 to control the voltage supplied to a DC machine 300. The DC machine includes a stator winding 302 and a rotor winding 304. Although shown as being in series connection with the stator winding 302, a rotor winding 304 may additionally or alternatively be arranged in parallel with the stator winding 302.

[0066] Thus, by controlling the switching of the switching devices 210, 230 the drive controller 410 controls operation of the machine 300, i.e., whether the machine is driven to rotate or not. The drive controller 410 can also control operation of a machine brake (not shown) connected to the machine 300, which can brake motion of the machine 300.

[0067] The drive controller 410 may be implemented using a general-purpose microprocessor executing a computer program stored on a storage medium to perform the operations described herein. Alternatively, the drive controller 410 may be implemented in hardware (e.g., ASIC, FPGA) or in a combination of hardware/software.

[0068] An energy harvesting device 320 is connected to the DC drive 240 by a first switching arrangement 340, arranged between the positive pole of the energy harvesting device 320 and a set of the switching devices 230, and by a second switching arrangement 350, arranged between the negative pole of the energy harvesting device 320 and the low side 290 of the DC bus 260. Each set of the switching devices 230 (i.e., each vertical branch) can be considered as a phase of the DC drive 240. The energy harvesting device 320 (which in this example is a solar panel) is selectively connectable to the DC drive 240 by operation of the first switching arrangement 340 and the second switching arrangement 350. The drive controller 410 in this example also provides a switching controller 400, that controls the first switching arrangement and the second switching arrangement 350. In particular, the switching controller 400 sends signals to the switching arrangements 340, 350 to control the switching arrangements 340, 350 to switch between a first condition (as shown in FIG. 7), in which the energy harvesting device 320 is disconnected from the DC drive 240, and a second condition (not shown) in which the energy harvesting device 320 is operatively connected to the DC drive 240, allowing power from the energy harvesting device 320 to be transferred back through the DC drive 240, and the converter 220 to the AC power source 280.

[0069] In this example, an additional inductor 380 is provided, between the positive node of the energy harvesting device 320 and the set of switching devices. However, alternatively, no additional inductor need be provided where the machine switches 370 are individually controllable, following a similar principle to that described above with reference to FIG. 6.

[0070] A method according to a second aspect of the present disclosure is illustrated in FIG. 8. In a first step, 600, movement of the machine of the conveyance system is driven using with power from the alternating current (AC) power source using the regenerative drive. Next, at step 602, power is harvested from the machine using the regenerative drive as the motion of the machine is being braked. Then, at step 604, a switching arrangement is switched from a first condition, in which an energy harvesting device is disconnected from the inverter of the regenerative drive, to a second condition in which the energy harvesting device is operatively connected to at least one phase of the inverter of the regenerative drive. Step 604 may take place when the machine is stationary.

[0071] It will be appreciated by those skilled in the art that the disclosure has been illustrated by describing one or more specific aspects thereof, but is not limited to these aspects; many variations and modifications are possible, within the scope of the accompanying claims.