Method and circuit for generating a pulse-width modulated actuating signal for a direct current actuator
First Claim
1. A method for generating a pulse-width modulated actuating signal for a direct current actuator, comprising the steps of:
- determining an actual value of a supply voltage that corresponds to a battery voltage, dividing a nominal value of the supply voltage by the actual value of the supply voltage in a first functional module in order to form a scaling factor, rescaling the scaling factor in a second functional module, and adapting a pulse duty factor from a saw-tooth wave that is dependant on a continuous actuating signal that is represented by a pulse width and whose amplitude corresponds to the actual value of the supply voltage.
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Abstract
Electrical direct current actuators, which have a distinct low-pass behavior with respect to the actuating signal, are frequently used in electronic control and regulation devices. Typical examples of such actuators are d.c. motors or electromagnets. In order to minimize the power losses when controlling such electric d.c. actuators, the associated power amplifiers usually are controlled by a pulse-width modulated actuating signal in the kHz frequency. In order to ensure that the actuator also is activated with the predefined actuating signal when there are variations in the supply direct voltage, the calculated actuating signal is multiplied by a scaling factor in a first functional module, with this scaling factor being obtained in another functional module on the basis of the relationship between the actual supply voltage and the nominal supply voltage. This rescaled actuating signal is then fed to the pulse-width modulator instead of the output actuating voltage causing the pulse duty factor to be adapted to the actual supply voltage.
35 Citations
12 Claims
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1. A method for generating a pulse-width modulated actuating signal for a direct current actuator, comprising the steps of:
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determining an actual value of a supply voltage that corresponds to a battery voltage, dividing a nominal value of the supply voltage by the actual value of the supply voltage in a first functional module in order to form a scaling factor, rescaling the scaling factor in a second functional module, and adapting a pulse duty factor from a saw-tooth wave that is dependant on a continuous actuating signal that is represented by a pulse width and whose amplitude corresponds to the actual value of the supply voltage. - View Dependent Claims (2, 3)
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4. A circuit for controlling a direct current actuator, comprising:
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a first functional module formed by program modules of a microprocessor, which calculates a scaling factor, a second functional module formed by program modules of the microprocessor, which is located downstream of the first functional module, wherein said second functional module multiplies a continuous actuating signal by the scaling factor, and a pulse-width modulator for generating a pulse-width modulated signal, which is located downstream of the second functional module, wherein said pulse-width modulator feeds the result to the direct current actuator. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12)
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Specification