Speed regulator for a brushless dc motor

• US 7,336,045 B2
• Filed: 05/26/2004
• Issued: 02/26/2008
• Est. Priority Date: 05/26/2003
• Status: Expired due to Fees

• Current Assignee: Innosource B.V.
• Original Assignee: Innosource B.V.
• Inventors: Clermonts, Franciscus Maria Henricus
• Primary Examiner(s): Donovan; Lincoln
• Assistant Examiner(s): Colon; Eduardo
• Application Number:
  US10/557,711
• Publication Number:
  US 20070029958A1
• Time in Patent Office: 1,371 Days
• Field of Search: None
• US Class Current: 318/400.29
• CPC Class Codes: H02P 6/06 Arrangements for speed regulation of a single motor wherein the motor speed is measured and compared with a given physical value so as to adjust the motor speed

Abstract

Speed regulator for a brushless DC motor, wherein the DC motor comprises a stator, a rotor and an electromagnet wherein the electromagnet is in the vicinity of the stator, the rotor produces a permanent magnetic field and the electromagnet is activated to generate an alternating magnetic field; furthermore comprising a power supply and a regulating element, the regulating element being connected to the power supply to regulate the power feed to the electromagnet, so that, during use, a torque generated by the DC motor is regulated, characterized in that the speed regulator is able to generate a voltage V(φ) as a function of rotor speed of revolution, rotor position (φ), rotor load and motor activation, wherein the speed regulator sets the change in the voltage V(φ) of the motor as a function of the rotor position φ in such a way that the instantaneous torque T(φ), at least in the vicinity of the reversal in polarity of the driving magnetic field, complies with the conditions that the derivative (φ)/∂φ is essentially zero and the second derivative ∂²T(φ)/∂φ² is an essentially monotonic function.

Claims

1. Speed regulator for a brushless DC motor, wherein the DC motor comprises a stator, a rotor and an electromagnet wherein the electromagnet is in the vicinity of the stator, the rotor produces a permanent magnetic field and the electromagnet is activated to generate an alternating magnetic field;

furthermore comprising a power supply and a regulating element, the regulating element being connected to the power supply to regulate the power feed to the electromagnet, so that, during use, a torque generated by the DC motor is regulated, wherein

the speed regulator is able to generate a voltage (V(φ

)) as a function of rotor speed of revolution, rotor position (φ

), rotor load and motor activation,

wherein the speed regulator sets the change in the voltage V((φ

)) of the motor as a function of the rotor position cp in such a way that the instantaneous torque T((φ

)), at least in the vicinity of the reversal in polarity of the driving magnetic field, complies with the conditions that

the derivative σ

T(φ

)/σ

φ

is essentially zero and

the second derivative σ

T²((φ

))/σ

φ

² is an essentially monotonic function.

2. Speed regulator for a brushless DC motor according to claim 1, wherein the instantaneous torque τ

(φ

), at least in the vicinity of a reversal in polarity of the driving magnetic field, essentially complies with

$T<br><br>\left(\mathrm{\phi <br><br>}\right)=\hat{T}<br><br>\left(\frac{1}{2}-\frac{1}{2}<br><br>\cos <br><br>\left(4<br><br>\mathrm{\phi <br><br>}\right)\right)$

where {circumflex over (T)} is an average value of the torque.

3. Speed regulation for a brushless DC motor according to claim 1, wherein the instantaneous torque T(φ

), at least in the vicinity of a reversal in polarity of the driving magnetic field, essentially complies with

$T<br><br>\left(\mathrm{\phi <br><br>}\right)=\hat{T}·<br><br>\left(\frac{1}{2}-\frac{1}{2}<br><br>\cos <br><br>\left(2<br><br>n<br><br><br><br>\mathrm{\phi <br><br>}\right)\right)$

where {circumflex over (T)} is an average value of the torque and n is the number of pole pairs of the stator.

4. Speed regulator for a brushless DC motor according to claim 1 wherein the regulating element (9) sets the change in the voltage V(φ

) of the motor as a function of the rotor position φ

.

5. Speed regulator for a brushless DC motor according to claim 1 wherein

the regulator also comprises a Buck regulator (3;

3-II), an H-bridge (4;

404;

3-II) and a drive regulator (5),

wherein the Buck regulator (3;

3-II) serves to generate the drive voltage |V(φ

)|, the Buck regulator (3;

3-II) is connected via its input to an output of the drive regulator (5) for receiving an activation signal and via its output to an input of the H-bridge (4;

404;

3-II) for transmitting the drive voltage V(φ

)

wherein the drive regulator (5) generates a high frequency low-voltage pulse width modulation signal (T+) as the activation signal.

6. Speed regulator for a brushless DC motor according to claim 5, wherein the Buck regulator (3) comprises a regulating transistor (T8) for regulating the voltage (V(φ

), a drive transistor (T9) for driving the regulating transistor (T8) and a pulse transformer (L2);

wherein the pulse transformer (L2) converts the high frequency low-voltage pulse width modulation signal (T+) into a high frequency activation signal for drive transistor (T9), and

wherein the activation signal is fed from the drive transistor (T9) to the gate of the regulating transistor (T8) so as to switch the regulating transistor (T8).

7. Speed regulator for a brushless DC motor according to claim 1, wherein the H-bridge (4;

404) comprises a first drive branch (4-1;

404-1) for driving the DC motor (1) via a first junction (J1) and a second drive branch (4-2;

404-2) for driving the DC motor (1) via a second junction (J2),

wherein the first drive branch (4-1;

404-1) comprises first and second drive transistors T4, T5) and the second drive branch (4-2;

404-2) comprises third and fourth drive transistors (T6, T7),

and wherein the first drive branch (4-1;

404-1) is provided with a first input (G2) and the second drive branch (4-2;

404-2) is provided with a second input (G1) for receiving a phase detection signal that has been derived from a rotor speed of revolution, rotor position (φ

) and rotor load.

8. Speed regulator for a brushless DC motor according to claim 1, wherein the regulator also contains a Hall sensor (6) and a regulating element (9),

wherein:

the Hall sensor (6) is equipped to pick up a signal from the rotor position (φ

) and the output of the Hall sensor (6) is connected to an input of the regulating element (9);

the regulating element (9) is provided with a voltage source (32) that can be regulated, one output of which is connected to an input of the drive regulator (5), for feeding back information from the signal picked up by the Hall sensor (6) to the drive regulator (5).

9. Speed regulator for a brushless DC motor according to claim 1, wherein the regulator also contains a current feedback unit (7), wherein:

the current feedback unit (7) is equipped to pick up a current signal from the current supplied to the DC motor (1;

motor) by the H-bridge (4;

404;

3-II), and the output of the current feedback unit (7) is connected to an input of the regulating element (9);

the regulating element (9) feeds back information from the current signal from current feedback unit (7) to the drive regulator (5) via the voltage source (32) that can be regulated.

10. Speed regulator for a brushless DC motor according to claim 1, wherein the regulator also contains voltage feedback unit (8);

wherein;

the voltage feedback unit (8) is equipped to pick up a voltage signal from the drive voltage I V((p) I generated by the Buck unit (3;

3-II) and the output of the voltage feedback unit (8) is connected to an input of the regulating element (9);

the regulating element (9) feeds back information from the voltage signal from voltage feedback unit (8) to the drive regulator (5) via the voltage source (32) that can be regulated.