Process for driving an alternating-current motor and an alternating current motor which can be driven in accordance with this process
First Claim
1. Method for driving an AC motor with speed control, comprising the steps of:
- pulse timing an AC motor voltage (UM) into pulse-width modulatable voltage pulses with a constant clock pulse frequency lying outside the hearing range;
controlling the motor speed by pulse-width modulation of said voltage pulses;
obtaining the AC motor voltage (UM) indirectly from a sinusoidal AC supply voltage (UN) by rectifying said supply voltage (UN) into a pulsating, unsmoothed DC voltage (UA1) having sinusoidal half-waves; and
controlling the polarity reversal of said DC voltage in accordance with the frequency of the AC supply voltage by means of two time overlap-free output signals (UK1, UK2) obtained from said AC supply voltage, so that said motor-voltage (UM) is essentially composed of the sinusoidal half-waves of said pulsating DC-voltage (UA1).
2 Assignments
0 Petitions
Accused Products
Abstract
Method and apparatus for driving an alternating-current motor. A sinusoidal supply AC voltage is rectified into a pulsating, unsmoothed DC voltage, with sinusoidal half waves and from this DC voltage an alternating-current motor voltage is produced by means of controllable polarity reversal. The pulse width of this alternating-voltage of the motor can be modulated. The polarity reversal takes place in accordance with the supply frequency in such a way that the AC voltage of the motor is essentially composed of the sinusoidal half waves of the pulsating DC voltage. For this purpose, the motor speed can be altered by changing the AC voltage of the motor with a constant timing frequency, lying outside the range of audibility, into pulse-width modulatable voltage pulses.
22 Citations
27 Claims
-
1. Method for driving an AC motor with speed control, comprising the steps of:
-
pulse timing an AC motor voltage (UM) into pulse-width modulatable voltage pulses with a constant clock pulse frequency lying outside the hearing range; controlling the motor speed by pulse-width modulation of said voltage pulses; obtaining the AC motor voltage (UM) indirectly from a sinusoidal AC supply voltage (UN) by rectifying said supply voltage (UN) into a pulsating, unsmoothed DC voltage (UA1) having sinusoidal half-waves; and controlling the polarity reversal of said DC voltage in accordance with the frequency of the AC supply voltage by means of two time overlap-free output signals (UK1, UK2) obtained from said AC supply voltage, so that said motor-voltage (UM) is essentially composed of the sinusoidal half-waves of said pulsating DC-voltage (UA1). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A speed controller for a controllable alternating-current motor with at least one motor winding comprises a supply voltage bridge rectifier circuit, an output stage connected with the rectifier circuit and with electronic switching elements provided in the output stage, wherein the motor winding is connected to one bridge shunt arm of the output stage and with a driver arrangement which is connected with the output stage and which drives the electronic switching elements and with a pulse-width modulator, connected with the switching elements, characterized in that:
the rectifier circuit (6) has outputs (A1, A2) which are connected with inputs (E1, E2) of the output stage (4) so that said rectifier circuit rectifies AC supply voltage and produces an unsmoothed, pulsating Dc voltage (UA1) with sinusoidal half waves is present at the inputs (E1, E2), the driver arrangement (10,
12) drives the electronic switching elements (T3 to T6) in accordance with the frequency of the ac supply voltage in such a way that at the outputs (M1, M2) of the output stage (4), connected with the motor winding (2), a motor AC voltage (UM) is present which is composed of the sinusoidal half waves of the pulsating direct current voltage (UA1), and wherein a control electrode (G) of one switching element in each (T5;
T6) of the switching elements, which are driven in paris, indirectly connected with the pulse-width modulator (16), which synchronizes at a constant, pulse-width modulatable timing frequency, so as to provide selective speed control of the motor.- View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
Specification