ELECTRIC MOTOR, AND DEVICE FOR GENERATING A SIGNAL FOR CONTROLLING THE SAME

• US 20110279076A1
• Filed: 12/24/2009
• Published: 11/17/2011
• Est. Priority Date: 01/24/2009
• Status: Active Grant

• Current Assignee: Ebm-Papst St Georgen GmbH & Company KG (Ebm-Papst Mulfingen GmbH & Company KG)
• Original Assignee: Ebm-Papst St Georgen GmbH & Company KG (Ebm-Papst Mulfingen GmbH & Company KG)
• Inventors: Hirt, Markus
• Granted Patent: US 8,686,678 B2
• Time in Patent Office: Days
• US Class Current: 318/503
• CPC Class Codes: H02P 7/28 using semiconductor devices
• CPC Class Codes: H02P 7/281 the DC motor being operated in four quadrants
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation

Abstract

An electric motor, having a stator (465), a rotor (470), and an apparatus for evaluating a signal provided for controlling said motor (110), comprises a receiving unit (430, 440) for receiving a control signal (PWM_mod), which is a pulse width modulated signal (PWM) onto which a data signal (DIR, DATA) is modulated.

An evaluation unit (440) is provided for evaluating the modulated control signal (PWM_mod). The unit is configured to extract, from the modulated control signal (PWM_mod), data provided for operation of the motor (110). The control apparatus includes a signal generator (450) configured to generate, on the basis of the extracted or ascertained data provided for operation of the motor (110), at least one control signal for the motor (110), such as a commanded direction of rotation. Piggybacking other control data onto the PWM power level signal reduces hardware investment, by permitting omission of a signal lead which would otherwise be required in the motor structure.

Claims

1. An apparatus for generating a signal for controlling an electric motor (110), comprising:

A) a signal generator (126) for generating a modulated control signal (PWM_mod) for driving the electric motor (110), which signal generator (126) is configured to generate said modulated control signal, from which the pulse duty factor of the PWM signal (PWM) can be derived, by modulating onto a PWM signal a data signal (DIR;

ADR;

DATA) having data provided for operating of the motor (110); and

B) a transmitting unit (127) which, in operation, transfers said modulated control signal (PWM_mod) to the motor (110).

2. The apparatus according to claim 1, in which the modulated control signal (PWM_mod) comprises, prior to modulation thereof with the data signal, successive signal elements (710, 720, 730) that each comprise a pulse off-time (712, 722, 732) having a predetermined off-time duration (T_L1) and a pulse (714, 724, 734) subsequent thereto having a predetermined pulse duration (T_L2), the off-time duration (T_L1) and pulse duration (T_L2) being correlated with an electrical power level to be applied to the motor (110).

3. The apparatus according to claim 2, wherein the signal generator (126) is configured to perform the steps of:

B1) ascertaining the off-time duration (T_L1);

B2) ascertaining the pulse duration (T_L2); and

B3) modifying the off-time duration (T_L1) and pulse duration (T_L2) of at least two signal elements (720, 730) as a function of data contained in the data signal (DIR;

ADR, DATA) while maintaining a predetermined value of said pulse duty factor.

4. The apparatus according to claim 1, wherein the signal generator (126) is configured, in order to specify a first rotation direction of said motor, to perform the steps of:

B3A) shortening the off-time duration (T_L1) of at least one first selected signal element (720) by an amount equal to a predetermined duration (T_D);

B3B) lengthening the pulse duration (T_L1) of the first signal element (720) by an amount equal to the predetermined duration (T_D);

B3C) lengthening the off-time duration (T_L1) of at least one second signal element (730) subsequent to the first selected signal element (720) by an amount equal to the predetermined duration (T_D); and

B3D) shortening the pulse duration (T_L2) of said second signal element (730) by an amount equal to the predetermined duration (T_D).

5. The apparatus according to claim 1, wherein the signal generator (126) is configured, in order to specify a second rotation direction of said motor, to perform the steps of:

B3A) lengthening the off-time duration (T_L1) of at least one first selected signal element (720) by an amount equal to a predetermined duration (T_D);

B3B) shortening the pulse duration (T_L2) of the first signal element (720) by an amount equal to the predetermined duration (T_D);

B3C) shortening the off-time duration (T_L1) of at least one second signal element (730) immediately subsequent to the first selected signal element (720) by an amount equal to the predetermined duration (T_D); and

B3D) shortening the pulse duration (T_L2) of the second signal element (730) by an amount equal to the predetermined duration (T_D).

6. The apparatus according to claim 1, wherein said transmitting unit (127) modulates the PWM signal onto the supply voltage (Ub) for the electric motor (110).

7. An electric motor having

a stator (465),

a rotor (470), and

an apparatus for evaluating a control signal (PWM_mod) deliverable in order to drive said motor (110), the improvement comprising

A) a receiving unit (430, 440) which receives the control signal (PWM_mod), which signal is constituted by modulating a pulse width modulated signal (PWM) with a data signal (DIR;

DATA) having data provided for operation of the motor (110), a predetermined pulse duty factor being extractable from the modulated control signal (PWM_mod);

B) an evaluation unit (440) which evaluates the modulated control signal (PWM_mod), which unit is configured to ascertain, on the basis of the modulated control signal (PWM_mod), data for operation of the motor (110) contained in said modulated control signal; and

C) an arrangement (450) which, in operation, generates, on the basis of said ascertained data, at least one driving signal for the motor (110).

8. The electric motor according to claim 7, wherein the evaluation unit (440) for evaluating the modulated control signal (PWM_mod) is configured to derive, from said modulated control signal, a pulse duty factor that is suitable for power level control of the motor (110).

9. The electric motor according to claim 7, wherein the evaluation unit (440) is configured to perform, in the context of evaluation of the modulated control signal (PWM_mod), the steps of:

B1) measuring the pulse duration (T_M2) of a reference signal element (810;

910);

B2) measuring the pulse duration (T_M4) of a first signal element (820;

920) subsequent thereto;

B3) measuring the pulse duration (T_M6) of a second signal element (830;

930);

B4) if the pulse duration (T_M2) of the reference signal element (810;

910) is greater than the pulse duration (T_M4) of the first signal element (820;

920) and less than the pulse duration (T_M6) of the second signal element (830;

930), controlling the motor (110) into operation in a first rotation direction; and

B5) if the pulse duration (T_M2) of the reference signal element (810;

910) is greater than the pulse duration (T_M4) of the second signal element (830;

930) and less than the pulse duration (T_M6) of the first signal element (820;

920), controlling the motor (110) into operation in a the second rotation direction.

10. A method for generating a signal of controlling an electrical load, which method comprises the steps of:

A) generating a pulse width modulated signal (PWM) having a predetermined pulse duty factor; and

B) modulating, onto said pulse width modulated signal, a data signal (DIR;

DATA) having data provided for operation of the load, in order to generate a modulated control signal (PWM_mod) from which said predetermined pulse duty factor of the pulse width modulated signal (PWM) is derivable.

11. The method according to claim 10, wherein the pulse width modulated signal (PWM) comprises successive signal elements (Block 1, Block 2, Block 3) that are each composed of

a pulse off-time having a predetermined off-time duration (T_L1) and a pulse subsequent thereto having a predetermined pulse duration (T_L2),

the off-time duration (T_L1) and the pulse duration (T_L2) being predetermined as a function of the power level to be delivered to the load.

12. The method according to claim 11, further comprising the steps of:

B1) ascertaining the off-time duration (T_L1);

B2) ascertaining the pulse duration (T_L2); and

B3) modifying the off-time duration (T_L1) and pulse duration (T_L2) of at least two signal elements (Block 1, Block 2, Block 3) as a function of data contained in the data signal (DIR) while maintaining a predetermined value of said pulse duty factor.

13. The method according to claim 12, wherein the data signal (DIR, DATA) specifies an operating parameter of the load.

14. The method according to claim 12, wherein

said modifying step B3) comprises:

B3A) shortening the off-time duration (T_L1) of at least one first selected signal element (Block 2) by an amount equal to a predetermined duration (T_D);

B3B) lengthening the pulse duration (T_L2) of the first signal element (Block 2) by an amount equal to the predetermined duration (T_D);

B3C) lengthening the off-time duration (T_L1) of at least one second signal element (Block 3) immediately subsequent to the first selected signal element (Block 2) by an amount equal to the predetermined duration (T_D); and

B3D) shortening the pulse duration (T_L2) of the second signal element (Block 3) by an amount equal to the predetermined duration (T_D).

15. The method according to claim 13, wherein said modifying step B3) for specifying a second operating parameter comprises:

B3A) lengthening the off-time duration (T_L1) of at least one first selected signal element (Block 2) by an amount equal to a predetermined duration (T_D);

B3B) shortening the pulse duration (T_L2) of the first signal element (Block 2) by an amount equal to the predetermined duration (T_D);

B3C) shortening the off-time duration (T_L1) of at least one second signal element (Block 3) immediately subsequent to the first selected signal element (Block 2) by an amount equal to the predetermined duration (T_D); and

B3D) shortening the pulse duration (T_L2) of the second signal element (Block 3) by an amount equal to the predetermined duration (T_D).