Controlling a power of an electrical motor

• US 8,125,179 B2
• Filed: 03/06/2008
• Issued: 02/28/2012
• Est. Priority Date: 03/09/2007
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Ettes, Wilhelmus, Otten, Wessel Adolf
• Primary Examiner(s): Ro, Bentsu
• Assistant Examiner(s): GLASS, ERICK DAVID
• Application Number:
  US12/529,547
• Publication Number:
  US 20100109598A1
• Time in Patent Office: 1,454 Days
• Field of Search: 318/811, 318/400.29, 318/400.3, 318/800, 318/801, 318/802, 361/23, 361/33
• US Class Current: 318/811
• CPC Class Codes: H02M 1/40 Means for preventing magnetic saturation
• CPC Class Codes: H02M 7/2176 comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output
• CPC Class Codes: H02P 25/14 Universal motors H02P25/12 takes precedence
• CPC Class Codes: H02P 7/30 using magnetic devices with controllable degree of saturation, i.e. transductors

Abstract

A motor control circuit (MC) comprising input terminals (IT1, IT2) to receive a rectified input voltage (Vrm), and output terminals (OT1, OT2) to supply a motor drive signal (Vm). A switching circuit (1) is alternately in an on-state (Ton) and an off-state (Toff) for intermittently coupling the input terminals (IT1, IT2) to the output terminals (OT1, OT2). A controller (2) controls the switching circuit (1) to be (i) in the on-state (Ton) during a first period in time (T1) when an amount of magnetic saturation of the motor is smaller than a predetermined value, and (ii) alternately in the on-state (Ton) and the off-state (Toff) to obtain a pulse width control of the motor drive signal (Vm) during a second period in time (T2) when the amount of magnetic saturation of the motor is larger than the predetermined value.

Claims

1. A motor control circuit (MC) comprising:

input terminals (IT1, IT2) for receiving a rectified input voltage (Vrm),

output terminals (OT1, OT2) for supplying a motor drive signal (Vm),

a switching circuit (1) being alternately in an on-state (Ton) and an off-state (Toff) for intermittently coupling the input terminals (IT1, IT2) to the output terminals (OT1, OT2),

a controller (2) for controlling the switching circuit (1) to be

(i) in the on-state (Ton) during a first period in time (T1) when an amount of magnetic saturation of the motor is smaller than a predetermined value, and

(ii) alternately in the on-state (Ton) and the off-state (Toff) to obtain a pulse width control of the motor drive signal (Vm) during a second period in time (T2) when the amount of magnetic saturation of the motor is larger than the predetermined value.

2. A motor control circuit (MC) as claimed in claim 1, further comprising:

a sense circuit (3) for sensing a value (PV) of a parameter for indicating the amount of saturation, and

a comparator (4) for comparing the value (PV) of the parameter with the predetermined value (RV) to obtain a comparison value (CV), and wherein the controller (2) is constructed for controlling the switching circuit (1) to be in the on-state (Ton) when the comparison value (CV) indicates that an amount of magnetic saturation of the motor is smaller than the predetermined value (RV).

3. A motor control circuit (MC) as claimed in claim 2, wherein the sense circuit (3) comprises a level detector (30) for detecting a level of the rectified input voltage (Vrm), and wherein the controller (2) is constructed for controlling the switching circuit (1) to be in the on-state (Ton) when the comparison value (CV) indicates that a value of the level of the rectified input voltage (Vrm) is smaller than the predetermined value (RV).

4. A motor control circuit (MC) as claimed in claim 2, wherein the sense circuit (3) comprises a detecting circuit (31) for detecting a zero level of the rectified input voltage (Vrm), and wherein the controller (2) is constructed for controlling the switching circuit (1) to be in the on-state (Ton) during a predetermined period in time (T1) after the zero level has been detected.

5. A motor control circuit (MC) as claimed in claim 2, wherein the sense circuit (3) comprises a detecting circuit (32) for detecting a ratio of a variation of a drive current (Im) supplied to the output terminals (OT1, OT2) and a variation of a drive voltage (Vm) across the output terminals (OT1, OT2), and wherein the controller (2) is constructed for controlling the switching circuit (1) to be in the on-state (Ton) when the ratio is larger than the predetermined value (RV).

6. A motor control circuit (MC) as claimed in claim 1, wherein the switching circuit (1) comprises a full bridge of electronic switches (S1, S2, S3, S4), and wherein the controller (2) is constructed for controlling the electronic switches (S1, S2, S3, S4) of the full bridge to obtain an AC motor drive signal (Vm).

7. A motor control circuit (MC) as claimed in claim 1, wherein the switching circuit (1) comprises a single switching device (S5) with internal freewheeling diode (D5) to obtain a DC motor drive signal (Vm).

8. A motor system comprising a motor (M) and a motor control circuit (MC) as claimed in claim 1, wherein the motor drive signal (Vm) is supplied to input terminals of the motor (M).

9. An appliance comprising the motor system of claim 8.

10. An appliance as claimed in claim 9 being one out of the group of vacuum cleaners, washing machines, shavers, blenders, kitchen machines.

11. A method of controlling a motor power comprising:

intermittently coupling (1) a rectified input voltage (Vrm) to the motor (M) during an on-state (Ton) and decoupling the rectified input voltage (Vrm) from the motor (M) during an off-state (Toff),

controlling (2) the intermittently coupling (1);

(i) to couple the rectified input voltage (Vrm) to the motor during a first period in time (T1) when an amount of magnetic saturation of the motor is smaller than a predetermined value, and

(ii) to alternately couple during the on-state (Ton) to, and to decouple during the off-state (Toff) from the motor (M) the rectified input voltage (Vrm) to obtain a pulse width control of the motor drive signal (Vm) during a second period in time (T2) when the amount of magnetic saturation of the motor (M) is larger than the predetermined value.