초록 ▼

An electric motor (40) has a permanent-magnet rotor (46) and an apparatus for generating a three-phase sinusoidal current (i202, i204, i206) for supplying current to said motor (40), also a microprocessor (95) for executing the following steps: while the motor (40) is running at a substantially cons

An electric motor (40) has a permanent-magnet rotor (46) and an apparatus for generating a three-phase sinusoidal current (i202, i204, i206) for supplying current to said motor (40), also a microprocessor (95) for executing the following steps: while the motor (40) is running at a substantially constant load, the motor is operated firstly at a predetermined operating voltage (U), and an amplitude of a current flowing to the motor is iteratively sampled, stored, and compared as applied voltage is decreased. If it is found, in this context, that the current flowing to the motor has not decreased as a result of reduction in the voltage amplitude, the motor (40) is operated at that current. If, however, it is found that the current flowing to the motor has decreased as a result of the reduction in the voltage delivered to the motor (40), the measurements and the comparison are repeated, optionally multiple times, in order to identify values for optimized efficiency.

대표청구항 ▼

1. A method of improving efficiency in a three-phase motor (40) having permanent-magnet excitation, a DC link power supply circuit including a current measuring element (56), and a control circuit (95) having an input coupled to an output of said current measuring element (56) and control outputs (A

1. A method of improving efficiency in a three-phase motor (40) having permanent-magnet excitation, a DC link power supply circuit including a current measuring element (56), and a control circuit (95) having an input coupled to an output of said current measuring element (56) and control outputs (A, B, C) coupled to respective phase windings of said motor, comprising the steps of: a) at a predetermined operating voltage (Û), operating the motor (40) at a load that deviates little or not at all from a predetermined value while performing additional steps;b) using said current measuring element to make a first sampling of amplitude of a current flowing to the motor (40) and storing a first measured value of said amplitude (S106, S108);c) reducing the amplitude of the voltage (Û) delivered to the motor (S110);d) making a second sampling of amplitude of the current flowing to the motor (40) and storing a second measured value of said amplitude;e) comparing said second measured amplitude value with said first measured amplitude value;f) if a result of said comparing step shows that the current flowing to the motor (40) has not decreased as a result of the reduction in the voltage amplitude (Û), operating the motor at that current;g) if said result of said comparing step shows that the current flowing to the motor (40) has decreased as a result of the reduction in the voltage (Û) delivered to the motor, repeating said sampling and comparing steps in order to identify values for optimized efficiency. 2. The method according to claim 1, further comprising operating the motor (40) at a substantially constant load in the context of measurements of current values, said current values being processed (S106-S116) to control operational parameters to improve efficiency. 3. The method according to claim 1, further comprising monitoring to detect any change in load, and, in case of detection of a change in load, repeating said sampling and comparing steps, in order to identify new values for optimized efficiency. 4. The method according to claim 1, further comprising an initial step of operating the motor by applying a predetermined voltage (Û) to terminals of a winding of the motor. 5. An electric motor (40) comprising a permanent-magnet rotor (46) and a stator (44);a DC link circuit (50-54) having first and second output leads (50) supplying electrical power to control circuits (42, 43) which in turn apply a respective current to each of a plurality of phase windings (U, V, W) which form part of said stator (44);a current measuring element (56) located in series with one of said first and second link circuit output leads (50) and generating an output signal (I) representing amplitude of total currents applied from said DC link circuit to said plurality of phase windings; andan apparatus (84-92) coupled to an output of said measuring element (56) and adapted to apply a respective sinusoidal currents (i202, i204, i206) to each respective one of said phase windings of said motor (40), anda microprocessor (95) configured to execute the steps of:a) at a predetermined operating voltage, operating the motor at a substantially constant load while performing additional steps;b) using said measuring element (56) to make a first sampling of amplitude of current (I) flowing to the motor (40) and storing a first measured value of said amplitude (S105, S108);c) reducing amplitude of voltage delivered to the motor (40);d) making a second sampling of amplitude of current flowing to the motor (40) and storing a second measured value of said amplitude;e) comparing said second measured amplitude value with said first measured amplitude value;f) if a result of said comparing step shows that the current flowing to the motor (40) has not decreased as a result of the reduction in the voltage amplitude, operating the motor at that current;g) if said result of said comparing step shows that the current flowing to the motor (40) has decreased as a result of the reduction in the voltage amplitude, repeating said sampling and comparing steps, in order to identify values for optimized efficiency. 6. The motor according to claim 5, wherein said microprocessor monitors to detect any change in motor load and, in case of detection of such a change, repeats said sampling and comparing steps until new values for optimized efficiency have been determined; and thereafter operates said motor using said new values. 7. The motor according to claim 6, further comprising three transducers adapted to generate three respective sinusoidal output signals, offset 120° with respect to each other; andthree pulse-width modulation generators (272, 274, 276) in each of which a sinusoidal signal is compared with an output signal from a triangular signal generator (268), in order to produce a respective control signal for controlling a respective phase of a three-phase inverter (42, 43). 8. The motor of claim 7, wherein the motor includes a inverter bridge circuit, andwherein said current measuring element (56, 264) is provided in said inverter bridge circuit, for measuring motor current as part of said motor current sampling and measuring steps. 9. The motor of claim 6, wherein the motor includes a inverter bridge circuit, andwherein said current measuring element (56, 264) is provided in said inverter bridge circuit, for measuring motor current as part of said motor current sampling and measuring steps. 10. The motor according to claim 5, further comprising three transducers adapted to generate three respective sinusoidal output signals, offset 120° with respect to each other; andthree pulse-width modulation generators (272, 274, 276) in each of which a sinusoidal signal is compared with an output signal from a triangular signal generator (268), in order to produce a respective control signal for controlling a respective phase of a three-phase inverter (42, 43). 11. The motor of claim 10, wherein the motor includes a inverter bridge circuit, andwherein said current measuring element (56, 264) is provided in said inverter bridge circuit, for measuring motor current as part of said motor current sampling and measuring steps. 12. The motor according to claim 5, wherein the microprocessor generates a signal which controls a rotating magnetic field of the motor and further indicates rotation speed of said motor. 13. The motor of claim 5, wherein the motor includes a inverter bridge circuit, andwherein said current measuring element (56, 264) is provided in said inverter bridge circuit, for measuring motor current as part of said motor current sampling and measuring steps.