CONTROL UNIT FOR CONTROLLING A MOTOR

Abstract

The invention relates to a control unit (1) for a motorized device (10) comprising: a brushless motor (20), a power supply (30), an operating unit (40), which can be activated by a user, wherein the control unit (1) is designed at least for controlling the commutation of the motor (20) by a plurality of circuit breakers (12, 13, 14, 15, 16, 17) connected to the power supply, and for initiating an electronic (i.e. in particular non-mechanical) braking of the motor, wherein the control unit (1) is deactivated, i.e. switched off, for a rotational speed-dependent duration to by means of a position sensor (50) and is held until then in an active switched-on operating state and, dependent thereon, a control means (60) is provided then to initiate, under automatic control, the shutdown of the device (10).

Claims

1-12. (canceled)

13. A control unit for a motorized device comprising: a brushless motor, a power supply, and an operating unit, that can be activated by a user; the control unit is designed at least for controlling the commutation of the motor by a plurality of power switches connected to the power supply, and for initiating an electronic, in particular non-mechanical, braking of the motor, when the control unit is deactivated, switched off, for a rotational speed-dependent duration t.sub.D after the detection of a specific motor condition or a defined point in time by a position sensor and is held until then in an active switched-on operating state and, dependent thereon, a controller is provided then to initiate, under automatic control, the shutdown of the device.

14. The control unit as set forth in claim 13, wherein the position sensor is a Hall sensor that transmits a signal to the control unit that is indicative of a motor condition.

15. The control unit as set forth in claim 13, wherein a memory is also provided were target values t.sub.D,TARGET for the rotational speed-dependent period t.sub.D are stored for a large number of motor speeds over an entire motor speed range.

16. The control unit as set forth in claim 13, wherein the control unit is configured in such a way that, after the time period t.sub.D has elapsed, the actual speed is detected and a check is performed as to whether the speed is greater than zero and the motor is still rotating and, in that case, the target value t.sub.D,TARGET stored in the memory for this speed is increased by a predetermined factor.

17. The control unit in claim 13, wherein the plurality of power switches have a plurality of high-side switches that are connected to a corresponding plurality of low-side switches, and the control unit is configured to switch the plurality of low-side switches and the plurality of high-side switches ON and OFF alternately in order to brake the motor.

18. The control unit in claim 13, wherein the operating unit has an ON/OFF switch that can be operated both manually and by the controller when a shutdown condition occurs.

19. The control unit as in claim 13, wherein a power contact is provided between the power supply and the control unit in order to ensure that current is made available to the control unit for the rotational speed-dependent duration t.sub.D when the ON/OFF switch has been switched off.

20. The control unit as in claim 18, wherein the controller detects the then-current speed immediately when the ON/OFF switch is switched off and from this the delay in shutdown over the duration t.sub.D is controlled and the device is switched off only when the stoppage of the motor is detected after the period t.sub.D has elapsed.

21. The control unit as in claim 13, further comprising an energy storage device, preferably a capacitor, where a specific amount of electrical energy is stored that is sufficient to provide the energy supply for a specific time period.

22. The control unit as set forth in claim 21, wherein the power supply of the controller is controlled after the ON/OFF switch is turned off by a predetermined discharge time by the stored energy in the capacitor, where a specific amount of electrical energy is stored that is sufficient to provide the energy supply for a specific time period.

23. A method for controlling a motor of a device, particularly with a control unit as set forth in in claim 13, with the following steps: a) initiating a shutdown command of the device; b) detecting the speed of the motor with speed detection at that point in time; c) identifying a holding period stored in a memory, namely a time span t.sub.D stored for the determined speed; d) controlling a braking process of the motor during the time periods t.sub.D by commutating the motor via a control unit; e) maintaining the active switched-on operating state for this time period t.sub.D; and f) shutting the device down only after the motor has come to a stop.

24. The method as set forth in claim 23, wherein the speed is detected again before step f), and step f) takes place only when a specific speed is reached or the speed is zero and it is therefore certain that the motor has come to a stop, and otherwise steps b) to e) are repeated, particularly successively, until the stoppage of the motor has been detected.

Description

DRAWINGS

[0041] FIG. 1 Is a schematic view of an embodiment of a configuration of a motor controller, and

[0042] FIG. 2 Is a schematic view of an exemplary circuit arrangement.

[0043] FIG. 3 Is a schematic view of a commutation profile at shutdown (once according to the prior art and once according to the present invention).

DETAILED DESCRIPTION

[0044] In the following, the disclosure will be described in greater detail on the basis of an exemplary embodiment with reference to FIGS. 1 and 2. The same reference symbols indicate the same functional and/or structural features.

[0045] FIG. 1 shows a schematic representation of an embodiment of a configuration of a motor control by a control unit 1 for a motor-driven device 10. The control unit 1 includes a brushless motor 20, a power supply 30, and an operating unit 40. The device 10 and its power supply can be activated by a user via an ON/OFF switch 41 on the operating unit 40.

[0046] Since the control unit is deactivated in the solutions known from the prior art as soon as the device 10 is switched off by the operating unit 40, a motor that is rotating at this point in time can no longer be braked in an electronically controlled manner. The embodiment of the disclosure is illustrated, as an example, that the control unit 1 has a plurality of power switches or circuit breakers 12, 13, 14, 15, 16, 17 for commutating the motor 20. The circuit breakers 12, 13, 14, 15, 16, 17 are connected to the power supply during the braking process, as shown in the circuit arrangement in FIG. 2.

[0047] After the initiation of an electronic braking of the motor 20, the control unit 1 deactivates for a respective rotational speed-dependent time period t.sub.D only after the stoppage of the motor has been detected by the position sensor 50.

[0048] Until then, the control unit 1 remains in an active switched-on operating state in the conventional manner. The control mechanism 60 is provided in order to automatically initiate the shutdown of the device 10.

[0049] The position sensor 50 shown in FIG. 1 is a Hall sensor in this exemplary embodiment. A memory 51 is also provided. This stores the target values t.sub.D,TARGET for the rotational speed-dependent duration t.sub.D for different motor speeds in the permissible motor speed range of the motor 20.

[0050] In the embodiment as shown in FIG. 2, a control mechanism 60 is provided. The control mechanism 60 introduces a predetermined delay between the shutdown command of the ON/OFF switch 41 and the shutdown of the Vcc voltage via a power contact to the controller 1. The control mechanism 60 can be configured with one or more energy storage components (e.g., capacitors) that are used to keep the power contact on for a predetermined time.

[0051] Alternatively, instead of or in addition to the control mechanism 60, the holding mechanism can also be implemented using software and executed via the controller 70. In particular, the controller 70 can be used to monitor the state of the switch 41. In this way, the controller 70 can monitor the trigger release and initiate braking even though the shutdown condition has already been activated.

[0052] Traditionally, electronic braking for BLOG motors has been implemented by turning on either the top or bottom MOSFETS in order to carry the braking current. In this approach, interruption has been achieved, for example, by continuously turning on all three low-side MOSFETs at once while keeping all three high-side MOSFETs off throughout the braking cycle, or vice versa.

[0053] According to the concept of the disclosure, an improved braking algorithm is provided where the braking current is divided between the high-side FETs 12, 13, 14 and the corresponding low-side FETs 15, 16, 17, via the driver components T1 and T2, in order to use all available MOSFETs for current reduction. In this embodiment, the high- and low-side MOSFETs 12, 13, 14, 15, 16, 17 turn ON and OFF alternately, sharing the current load needed for electronic braking. However, another algorithm for controlling the circuit breakers during braking is also conceivable.

[0054] FIG. 3 shows a schematic profile at shutdown (once according to the prior art and once according to the present disclosure). In the upper curve (a) (prior art), braking takes place in the time period t1 to t2 (during the corresponding commutation phase). Curve (b) represents the shutdown period. The braking process thus starts at t1, while shutdown does not take place until time t3 is reached. Accordingly, the shutdown time begins at t1 and ends at t3.

[0055] In the solution according to the disclosure (curve c), these phases are consecutive. The braking process takes place in the time period t1 to t2 and then (as indicated by the arrows) the shutdown process follows, which ends at time t4. The device according to the disclosure is thus active for a longer period of time. This phase is also referred to as the “shutdown” phase.

[0056] The disclosure is not limited in its execution to the above mentioned preferred exemplary embodiments. Rather, a number of variants are conceivable that make use of the illustrated solution even in the form of fundamentally different embodiments.

[0057] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.