POWER PROTECTION DEVICE AND METHOD

Abstract

A power protection device for protecting a load, with: a surge protection unit (110) for generating a surge detection signal (S H ), if the power supply (P) of the load (150) is above an upper limit of a specified voltage range; an undervoltage protection unit (120) for generating an undervoltage detection signal (S L ), if the power supply (P) of the load (150) is below a lower limit of the specified voltage range; a work state detection unit (130) for receiving a control signal (Sc) from outside and generating a work state detection signal (S) S ), if the level time change rate of the control signal (Sc) is above a time change rate threshold; and a power control unit (140) which is connected to the overvoltage protection unit (110), the operating state detection unit (130) and the undervoltage protection unit (120) for controlling the on and off state of the power supply (P) according to the overvoltage detection signal (S H ), the undervoltage detection signal (S L ) or the operating status detection signal (S S ) is connected wherein the power control unit (140) switches off the power supply (P) when the overvoltage detection signal (S) H ), the undervoltage detection signal (S L ) or the operating status detection signal (S S ) is received.

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to power protection devices for motors, and in particular to power protection devices that save energy. Description of the state of the art

[0002] The state of the art provides various circuit protection methods to protect the expensive and sensitive motors from damage.

[0003] The state of the art provides three methods for overvoltage protection: Method I - improving circuit element specifications; Method II - protecting circuits by using a transient voltage suppressor (TVS); and Method III - protecting circuits by using an operational amplifier (OP).

[0004] In Method I, improving circuit element specifications leads to increased costs and a reduced choice of circuit elements. Consequently, Method I can only be applied to simple circuits and is rarely implemented. In Method II, although the use of TVS is the primary approach, this method can only be used to eliminate high transient voltages or low-power current surges, such as ESD, and circuits can burn out if the high voltage persists. In Method III, the use of an op-amp results not only in higher costs and a limited input voltage, but also in a more complex circuit design and a slower circuit response time.

[0005] US 2003 / 0 063 900 A1 describes a method and system for linear speed control of DC electric motors, with an over / undervoltage detection circuit for monitoring the voltage of the electric motor.

[0006] DE 10 2004 055 073 A1 describes a control system for controlling a DC motor. A controller regulates the operation of the motor. A voltage sensor measures the voltage supplied to the motor. A speed sensor receives a measured speed of the motor, and a conditioning circuit 21 receives a speed signal and conditions the speed signal to supply the controller with a nominal speed based on the voltage supplied to the motor.

[0007] US 2011 / 0 063 759 A1 describes a hybrid circuit for protecting a connected load with overvoltage and undervoltage monitoring.

[0008] US 4 636 711 A describes a voltage control device for an inductive load.

[0009] US 7 489 855 B2 describes a control system for controlling a load.

[0010] EP 0 160 163 A1 describes an airflow control device with a fan motor rotating at a speed corresponding to the frequency of a power supply; with a variable frequency power source connected to the motor; with a control device for supplying a control signal to the power source to determine its output frequency; and with a deviation signal detector comprising means for detecting deviations in the control signal supplied to the power source from normal values. BRIEF DESCRIPTION OF THE INVENTION

[0011] The problem is solved by characteristics of independent claims.

[0012] The present invention provides a power protection device for protecting a load.The device comprises an overvoltage protection unit for generating an overvoltage detection signal when the power supply to the load is above the upper limit of a predetermined voltage range; an undervoltage protection device for generating an undervoltage detection signal when the power supply to the load is below the lower limit of the predetermined voltage range; an operating state detection unit for receiving a control signal and generating an operating state detection signal when the level time change rate of the control signal is above a time change rate threshold; and a power control unit connected to the overvoltage protection device, the operating state detection unit, and the undervoltage protection device for controlling the on and off states of the power supply according to the overvoltage detection signal, the undervoltage detection signal, and the operating state detection signal.

[0013] The present invention provides a power protection method for protecting a load. The method comprises: generating an overvoltage detection signal when the load's power supply is above the upper limit of a predetermined voltage range; generating an undervoltage detection signal when the load's voltage supply is below the lower limit of the predetermined voltage range; receiving a control signal and generating an operating state detection signal when the control signal's level change rate is above a time change rate threshold; and switching off the power supply when an overvoltage detection signal, an undervoltage detection signal, or an operating state detection signal is received. A detailed description is given in the following embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention can be fully understood by reading the following detailed description and examples with reference to the attached drawings, wherein: Fig. 1 shows a block diagram of the power protection device according to an embodiment of the present invention; Fig. 2A shows a schematic diagram of the surge protection unit according to an embodiment of the present invention; Fig. 2B the signals in the surge protection unit from Fig. 2A shows; Fig. Figure 3A shows a schematic diagram of the undervoltage protection unit according to an embodiment of the present invention; Fig. 3B the signals in the undervoltage protection unit from Fig. 3A shows; Fig. 4A shows a schematic diagram of the operating state detection unit according to an embodiment of the present invention; Fig. 4B the signals in the operating state detection unit from Fig. 4A shows; Fig. Figure 5 shows a flowchart of the power protection procedure according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following description is given in the manner considered best for carrying out the invention. This description serves to illustrate the general principles of the invention and should not be understood as limiting. The scope of protection of the invention is best defined by reference to the appended claims.

[0016] The power protection device of the present invention is used to protect a fan motor. Fig. Figure 1 shows a power protection device according to an embodiment of the present invention. In this embodiment, the motor 150 receives a power supply P from a power source via a power management unit 160, and the rotational speed of the motor 150 is controlled by a rotational speed control signal Sc, which is received externally via a micro control unit 170.

[0017] The present invention provides a specific power protection device 100, wherein the power protection device 100 is connected to the motor 150. The power protection device 100 of the present invention comprises an overvoltage protection unit 110, an undervoltage protection unit 120, a working state detection unit 130, and a power control unit 150. The components of the present invention are arranged according to the Fig. 2A, Fig. 2B, Fig. 3A, Fig. 3B, Fig. 4A and Fig. 4B is described in more detail in the following paragraphs.

[0018] Fig. Figure 2A shows a schematic diagram of the surge protection unit 110 according to an embodiment of the present invention. Fig. 2B shows the signals in the surge protection unit 110. Fig. 2A. The overvoltage protection unit 110 of the present invention can generate an overvoltage detection signal when the power supply P of the motor is above the upper limit V+ of a predetermined voltage range. The overvoltage detection signal can be used by the power control unit 140, which will be described later. As in Fig. As shown in Figure 2A, the overvoltage protection unit 110 of the present invention comprises a voltage subtractor 112. The voltage subtractor 112 can subtract the portion of the power supply P that lies above the upper limit V+ of the specified voltage range in order to directly generate an overvoltage detection signal. As shown in Figure 2A, the overvoltage protection unit 110 of the present invention comprises a voltage subtractor 112. The voltage subtractor 112 can subtract the portion of the power supply P that lies above the upper limit V+ of the specified voltage range in order to directly generate an overvoltage detection signal. Fig. As shown in Figure 2B, if the power supply P has a portion that exceeds the upper limit V+ of the specified voltage range, the voltage subtractor 112 can directly subtract this portion and generate an "overvoltage detection signal SH" (high level). In other words, if the power supply P is not above the upper limit V+ of the specified voltage range, the voltage subtractor 112 will not affect the original level of the power supply P and will not generate an overvoltage detection signal. In some embodiments, the voltage subtractor 112 includes at least one Zener diode. With the aforementioned structure, the overvoltage protection unit 110 of the present invention does not have a TSV or OP according to the prior art, which consume additional power, thus saving energy. As shown in Figure 2B, the voltage subtractor 112 can be used to measure the voltage of the power supply P. Fig. As shown in Figure 2A, the overvoltage protection unit 110 of the present invention can further comprise a control circuit 114. The control circuit 114 can regulate the signals provided by the voltage subtractor 112 so that the signals have an ideal waveform that can be accepted by the power control unit 140 (for example, the square waveform of the overvoltage detection signal SH', as shown in Figure 2A). Fig. 2B), which prevents malfunctions.

[0019] Fig. Figure 3A shows a schematic diagram of the undervoltage protection unit 120 according to an embodiment of the present invention. Fig. 3B shows the signals in the undervoltage protection unit 120. Fig. 3A. In contrast to the overvoltage protection unit 110, the undervoltage protection unit 120 of the present invention can generate an undervoltage detection signal when the power supply P of the motor is below the lower limit V- of the specified voltage range. The undervoltage detection signal can be used by the power control unit 140, which will be described later. In a Fig. In the embodiment shown in Figure 3A, the undervoltage protection unit 120 of the present invention comprises a voltage subtractor 122. The voltage subtractor 122 can subtract the portion of the power supply P that lies below the lower limit V- of the specified voltage range in order to directly generate the undervoltage detection signal. As shown in Figure 3A, the undervoltage protection unit 120 comprises a voltage subtractor 122. Fig. As shown in Figure 3B, the voltage subtractor 122 filters out this part and generates an undervoltage detection signal S. L(low level) when the power supply P has a portion that is below the lower limit V- of the specified voltage range. In other words, if the power supply P is not below the lower limit V- of the specified voltage range, the voltage subtractor 122 will not affect the original level of the power supply P and will not generate an undervoltage detection signal. In some embodiments, the voltage subtractor 122 includes at least one Zener diode. With the structure just described, the undervoltage protection unit 120 of the present invention does not have a TSV or OP according to the prior art that would consume additional power, thus saving energy. As in Fig. As shown in Figure 3A, the undervoltage protection unit 120 of the present invention further comprises a controller circuit 124. The controller circuit 124 can regulate the signals provided by the voltage subtractor 122 so that the signals have waveforms that can be accepted by the power control unit 140 (for example, those shown in the Fig. 3A shows the rectangular waveform of the undervoltage detection signal S L ) and can prevent malfunctions.

[0020] Fig. Figure 4A shows a schematic diagram of the working state detection unit 130 according to an embodiment of the present invention. Fig. 4B shows the signals in the operating status detection unit 130. Fig. 4A. The operating state detection unit 130 of the present invention is configured to receive the rotational speed control signal Sc. As shown in Fig. As shown in Figure 4A, the operating state detection unit 130 generates an operating state detection signal S S , if the rate of change of the rotational speed control signal Sc exceeds a rate of change threshold. The operating state detection signal S S can be used by the power control unit 140, which will be described later. As in Fig. As shown in Figure 4B, the operating state detection unit 130 of the present invention further comprises a signal converter 132. In one embodiment, the signal converter 132 comprises a charge / discharge circuit (for example, an RC circuit) that can control the charge / discharge characteristic of the circuits. As shown in Figure 4B, the operating state detection unit 130 of the present invention further comprises a signal converter 132. In one embodiment, the signal converter 132 comprises a charge / discharge circuit (for example, an RC circuit) that can control the charge / discharge characteristic of the circuits. Fig. As shown in 4b, the signal converter 132 can convert the rotational speed control signal Sc, which has a different rotational speed in one period, into a working state detection signal S. S(low level) through the charging and discharging characteristics of the circuits. As in Fig. As shown in Figure 4A, the operating state detection unit 130 of the present invention further comprises a controller circuit 134. The controller circuit 134 regulates the signals provided by the signal converter 132 so that the signals have waveforms that can be accepted by the power control unit 140 (for example, those shown in the Fig. 4B shows the rectangular waveform of the operating state detection signal S S ) to prevent malfunctions.

[0021] The power control unit 140 of the present invention is connected to the overvoltage protection unit 110, the undervoltage protection unit 120 and the operating state detection unit 130 in order to detect the on and off state of the power supply P according to the overvoltage detection signal S H (or S H' ), the undervoltage detection signal S L (or SL' ) and the operating status detection signal S S (or S S' ) to control. In particular, the power control unit comprises 140 logic elements (such as AND and OR gates) and can switch off the power supply P of the motor 150 when an overvoltage detection signal S is received. H (or S H' ), an undervoltage detection signal S L (or S L' ) or a work status detection signal S S (S S' ) are detected. In other words, if neither the overvoltage detection signal S H (or S H' ), the undervoltage detection signal S L (or S L' ) also the operating status detection signal S S (or S S') is detected by the power control unit 140, indicating that the power supply P and the rotational speed control signal Sc are in a normal state and that the power supply P can safely operate the motor 150. The present invention thus provides a variety of protective devices for the motor 150. In some embodiments, as in Fig. As shown in Figure 1, the power control unit 140 controls the motor 150 via the power management unit 160 and the micro control unit 170. However, in other embodiments, the present invention should not be limited to this.

[0022] In order to save energy, in a preferred embodiment of the present invention, the operating state detection unit 130 and the undervoltage protection unit 120 are both connected between the overvoltage protection unit 110 and the power control unit 140, so that they can immediately stop operation as soon as they receive the overvoltage detection signal S H received.

[0023] According to the power protection device described above, the present invention also provides a power protection method. Fig.Figure 5 shows a flowchart of the power protection method according to an embodiment of the present invention. The power protection method is used to protect a motor. The method comprises the following steps: generating an overvoltage detection signal when the motor's power supply is above the upper limit of a predetermined voltage range (step S502); generating an undervoltage detection signal when the motor's power supply is below the lower limit of the predetermined voltage range (step S504); receiving a speed control signal and generating an operating state detection signal when the level time change rate of the speed control signal is above a time change rate threshold (step S506); and switching off the power supply when the overvoltage detection signal, the undervoltage detection signal, or the operating state detection signal is received (step S508).Since the person skilled in the art can understand the power measurement method of the present invention by reference to the power protection device described above, the details of the power protection method will not be described further.

[0024] While the invention has been described by way of example and according to a preferred embodiment, it should be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to protect various modifications and similar arrangements (as may be obvious to a person skilled in the art). Consequently, the scope of protection of the attached drawings should be interpreted in the broadest possible way to encompass all such modifications and similar arrangements.

Claims

[1] A power protection device for protecting a load, comprising: an overvoltage protection unit (110) for generating an overvoltage detection signal (S H ) when a power supply (P) of the load (150) is above an upper limit of a predetermined voltage range; an undervoltage protection unit (120) for generating an undervoltage detection signal (S L ) when the power supply (P) of the load (150) is below a lower limit of the predetermined voltage range; a working state detection unit (130) for receiving a control signal (Sc) from the outside and generating a working state detection signal (S S ) if a level time change rate of the control signal (Sc) is above a time change rate threshold; and a power control unit (140) connected to the overvoltage protection unit (110), the working state detection unit (130) and the undervoltage protection unit (120) for controlling the on and off state of the power supply (P) according to the overvoltage detection signal (S H ), the undervoltage detection signal (S L ) or the working state detection signal (S S ) is connected wherein the power control unit (140) switches off the power supply (P) when the overvoltage detection signal (S H ), the undervoltage detection signal (S L ) or the working state detection signal (S S ) is received. [2] The power protection device according to claim 1, wherein the working state detection unit (130) is connected between the overvoltage protection unit (110) and the power control unit (140), and turns off when the overvoltage detection signal (S H ) is received. [3] Power protection device according to one of the preceding claims, wherein the undervoltage protection unit (120) is connected between the overvoltage protection unit (110) and the power control unit (140), and switches off when the overvoltage detection signal (S H ) is received. [4] Power protection device according to one of the preceding claims, wherein the overvoltage protection unit (110) comprises: a voltage subtractor (112) for subtracting a part of the power supply (P) which is above the upper limit of the predetermined voltage range in order to obtain the overvoltage detection signal (S H ) to generate. [5] The power protection device of claim 4, wherein the voltage subtractor (112) comprises at least one Zener diode. [6] Power protection device according to one of the preceding claims, wherein the overvoltage protection unit (110) further comprises a regulator circuit (114) for regulating the signals (S H ) so that the signals conform to a waveform that can be accepted by the power control unit (140) and malfunctions are avoided. [7] Power protection device according to one of the preceding claims, wherein the undervoltage protection unit (120) comprises a voltage subtractor (122) for subtracting a part of the power supply (P) which is below the lower limit of the predetermined voltage range in order to obtain the undervoltage detection signal (S L ) directly. [8] The power protection device of claim 7, wherein the voltage subtractor (122) comprises at least one Zener diode. [9] Power protection device according to one of the preceding claims, wherein the undervoltage protection unit (120) further comprises a regulator circuit (124) for regulating the voltage supplied by the voltage subtractor (S L ) so that the signals conform to a waveform that can be accepted by the power control unit (140) and malfunctions are avoided. [10] Power protection device according to one of the preceding claims, wherein the working state detection unit (130) comprises a signal converter. [11] The power protection device according to claim 10, wherein the signal converter (132) comprises a charge / discharge circuit for controlling a charge time and a discharge time. [12] Power protection device according to claim 10 or 11, wherein the signal converter (132) comprises an RC circuit. [13] Power protection device according to one of the preceding claims, wherein the working state detection unit (130) further comprises a regulator circuit (134) for regulating a signal (S S ) so that the signal satisfies a waveform accepted by the power control unit (140) and malfunctions are avoided. [14] Power protection device according to one of the preceding claims, wherein the power control unit (140) comprises logic elements. [15] Power protection device according to one of the preceding claims, wherein the power supply unit (140) comprises AND and OR gates. [16] Power protection method for protecting a load, comprising the steps: Generating (S502) an overvoltage detection signal (S H ) when a power supply (P) of the load (150) is above an upper limit of a predetermined voltage range; Generating (S504) an undervoltage detection signal S L when the power supply (P) of the load (150) is below a lower limit of the predetermined voltage range; Receiving (S506) a control signal (Sc) from the outside and generating a working state detection signal (Ss) when a level time change rate of the control signal (Sc) is above a time change rate threshold; and Turn off (S508) the power supply (P) when the overvoltage detection signal (S H ), the undervoltage detection signal (S L ) or the working state detection signal (Ss) is received.

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