Method and circuit arrangement for protecting an electric motor from an overload
First Claim
1. A method of activation of an emergency operation controller for protecting an electric motor (10) and/or its trigger circuit (12) against overload, wherein the electric motor is assigned a motor end stage for pulse-width modulated control (PWM) of the power supplied and is also assigned a controller for limiting the motor power on the occurrence of an elevated supply voltage, the method comprising providing an overload protection which becomes operative in emergency operation of the electric motor (10) by activation of an emergency operation controller (14, 16) upon the occurrence of a malfunction (28, 30) in the triggering circuit (12) of the motor end stage, and supplying electric motor (10) with a defined emergency-operation power, which below a first overvoltage threshold (Us1) of the supply voltage has a specified value or course and is reduced or switched off if one or more overvoltage thresholds (Us1 Us2) are exceeded.
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Accused Products
Abstract
A method and a circuit for protecting an electric motor and/or its trigger circuit against overload in the emergency-operation mode in a motor vehicle direct-current fan motor operated by means of pulse width modulation, in which the trigger circuit is designed as an emergency-operation controller, with a microcontroller preceding the motor end stage and with a comparator assembly for detecting overvoltages. Overload protection is assured at elevated battery voltage and at the same time when the emergency-operation controller is activated in response to malfunctions in the normal triggering of the electric motor. To that end, at least one overvoltage threshold (Us1, Us2) is defined; when it is exceeded, the power supplied to the motor is reduced or switched off.
61 Citations
20 Claims
- 1. A method of activation of an emergency operation controller for protecting an electric motor (10) and/or its trigger circuit (12) against overload, wherein the electric motor is assigned a motor end stage for pulse-width modulated control (PWM) of the power supplied and is also assigned a controller for limiting the motor power on the occurrence of an elevated supply voltage, the method comprising providing an overload protection which becomes operative in emergency operation of the electric motor (10) by activation of an emergency operation controller (14, 16) upon the occurrence of a malfunction (28, 30) in the triggering circuit (12) of the motor end stage, and supplying electric motor (10) with a defined emergency-operation power, which below a first overvoltage threshold (Us1) of the supply voltage has a specified value or course and is reduced or switched off if one or more overvoltage thresholds (Us1 Us2) are exceeded.
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16. A method of activation of an emergency operation controller for protecting an electric motor (10) and/or its trigger circuit (12) against overload, wherein the electric motor is assigned a motor end stage for pulse-width modulated control (PWM) of the power supplied and is also assigned a controller for limiting the motor power on the occurrence of an elevated supply voltage, the method comprising providing an overload protection which becomes operative in emergency operation of the electric motor (10) by activation of an emergency operation controller (14, 16) upon the occurrence of a malfunction (28, 30) in the triggering circuit (12) of the motor end stage, and supplying electric motor (10) with a defined emergency-operation power, which below a first overvoltage threshold Us1 of the supply voltage has a specified value or course and is reduced or switched off if one or more overvoltage thresholds (Us1 Us2) are exceeded, further comprising regulating the power of the electric motor (10) in the emergency-operation mode by means of a voltage monitoring circuit with a comparator assembly (14), to which a reference voltage (Uref) corresponding to the battery voltage (Ubat) is supplied as a reference value for the overvoltage thresholds (Us1, Us2).
- 17. In a circuit arrangement for protecting an electric motor and/or its trigger circuit (12) against overload, the circuit arrangement comprising a motor end stage for pulse-width modulated control (PWM) of the power supplied to the electric motor, a controller for limiting the motor power on the occurrence of an elevated supply voltage, the improvement wherein, for the overload protection in the emergency-operation mode of the electric motor (10), the trigger circuit (12) is embodied as an emergency-operation controller (14, 16, 22), which in addition to a PWM set-point value transducer (18) and the motor end stage (22) has a microcontroller (16), which precedes the motor end stage and which upon an interruption or a defective input of the set-point value signal of the pulse width modulation (PWMso11) and/or of a switched supply voltage (U15) supplies a control voltage (PWM) to the motor end stage (22), corresponding to the specification of at least one overvoltage threshold (Us1, Us2) to the microcontroller.
Specification