Overmodulation of electric motor in power steering system
AssigneeValeo Electrical Systems, Inc.
InventorSergei Kolomeitsev
Life of this patent
Estimating the term…
Abstract
A control system for an electric motor, of the type used to deliver mechanical power to a power-steering system in a vehicle. In one form of the invention, at high motor speeds, an inverter is requested to deliver a pseudo-sinusoidal voltage having peak-to-peak value which a vehicle battery cannot attain. Consequently, the pseudo-sinusoidal voltage delivered to the motor is clipped at some value: the tops, and bottoms, of the pseudo-sinusoid peaks are chopped off. This clipping brings current in the phases closed to being in-phase with the voltage.
Claims23
An apparatus, comprising:
- a) an electric motor having independent phases;
- b) an inverter which delivers pseudo-sinusoidal voltage to the phases;
- and
- c) torque-boosting means for detecting whether motor speed exceeds a threshold and, if so, inducing clipping in the pseudo-sinusoidal voltage.
An apparatus comprising:
- a) an electric motor having phases;
- and
- b) means for increasing modulation index of voltage supplied to the motor when direct current Id in the phases increases.
A method, comprising the steps of:
- a) maintaining an electric motor having independent phases;
- b) maintaining an inverter which delivers pseudo-sinusoidal voltage to the phases;
- and
- c) detecting whether motor speed exceeds a threshold and, if so, inducing clipping in the pseudo-sinusoidal voltage.
An apparatus comprising:
- a) an electric motor having phases;
- and
- b) means for increasing modulation index of voltage supplied to the motor when direct current Id in the phases increases.
A method comprising the steps of:
- a) maintaining an electric motor having phases;
- and
- b) increasing modulation index of voltage supplied to the motor when direct current Id in the phases increases.
A method of operating an electric motor, comprising:
- a) detecting whether motor speed has reached a first threshold T1;
- b) if the threshold T1 has been reached,
- i) continually increasing direct current Id in phases of the motor as speed further increases;
- and
- ii) increasing modulation index of voltage delivered to the motor as speed increases from threshold T1 to threshold T2, and then holding modulation index substantially constant above threshold T2.
An apparatus, comprising:
- a) an electric motor;
- b) means for detecting whether motor speed has reached a first threshold T1, and if the threshold T1 has been reached,
- i) continually increasing direct current Id in phases of the motor, as speed further increases;
- and
- ii) increasing modulation index of voltage delivered to the motor as speed increases from threshold T1 to threshold T2, and then holding modulation index substantially constant above threshold T2.
An apparatus comprising:
- a) a power supply delivering a voltage V;
- b) a motor having phase coils in a synchronous-type stator;
- c) a system for providing Field Oriented Control to the motor;
- and
- d) a controller for detecting whether motor speed exceeds a threshold and, if so,
- i) continually increasing Id as speed increases;
- and
- ii) initially increasing modulation index of voltage applied to the motor as speed increases, and then holding modulation index constant.
A system comprising:
- a) an electric motor;
- b) a controller which
- i) at speeds below a threshold T1, delivers voltage to the motor at a modulation index of 1.0 and maintains direct current, Id, at zero;
- ii) at speeds above threshold T1 and below threshold T2, delivers voltage to the motor at a modulation index exceeding 1.0 and increasing with motor speed, and maintains direct current, Id, above zero;
- and
- iii) at speeds above threshold T2, delivers voltage to the motor at a modulation index exceeding 1.0 and held fixed, and maintains direct current, Id, above zero.
Dependencies are inferred from the claim text.