Method and device for determining the rotary speed of an electrical machine
First Claim
1. A method for determining a rotary speed of an electrical machine, which is controlled in PWM operation, the method comprising:
- ascertaining the rotary speed from a tracking voltage, which is measured in a turnoff phase;
estimating the rotary speed in the PWM phase with the aid of a mathematical model, wherein the rotary speed is ascertained in the PWM phase with the aid of a recursive function
ω
i=ω
i−
1+Δ
ω
, where Δ
ω
=f(Uk,ω
i−
1);
andcontrolling the electrical machine using a control signal, which has a PWM phase in which the electrical machine is periodically switched on and off using a prespecified pulse duty factor, and which has a measuring phase in which the electrical machine is switched off and the tracking voltage is measured.
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Accused Products
Abstract
A method for determining the rotary speed of an electrical machine, especially of a direct current motor, which is controlled in PWM operation, the tracking voltage of the electrical machine being measured and the rotary speed being ascertained from that. The rotary speed fluctuations are able to be substantially reduced if the electrical machine is controlled using a control signal which has a PWM phase, in which the electrical machine is periodically switched on and off using a prespecified pulse duty factor, and which has a measuring phase in which the electrical machine is switched off. The rotary speed is measured in the measuring phases, in this instance, and is calculated in the PWM phases based on a model.
7 Citations
19 Claims
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1. A method for determining a rotary speed of an electrical machine, which is controlled in PWM operation, the method comprising:
-
ascertaining the rotary speed from a tracking voltage, which is measured in a turnoff phase; estimating the rotary speed in the PWM phase with the aid of a mathematical model, wherein the rotary speed is ascertained in the PWM phase with the aid of a recursive function
ω
i=ω
i−
1+Δ
ω
, where Δ
ω
=f(Uk,ω
i−
1);and controlling the electrical machine using a control signal, which has a PWM phase in which the electrical machine is periodically switched on and off using a prespecified pulse duty factor, and which has a measuring phase in which the electrical machine is switched off and the tracking voltage is measured. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device for determining a rotary speed of an electrical machine, which is controlled in PWM operation, comprising:
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a voltage sensor for measuring a tracking voltage; an electronic system for determining the rotary speed from the measured tracking voltage; an arrangement for estimating the rotary speed in the PWM phase with the aid of a mathematical model, wherein the rotary speed is ascertained in the PWM phase with the aid of a recursive function
ω
i=ω
i−
1+Δ
ω
, where Δ
ω
=f(Uk,ω
i−
1);and an arrangement for controlling the electrical machine using a control signal, which has a PWM phase in which the electrical machine is periodically switched on and off using a prespecified pulse duty factor, and which has a measuring phase in which the electrical machine is switched into a regenerative operation and the tracking voltage is measured. - View Dependent Claims (10)
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11. A device for determining a rotary speed of an electrical machine, which is controlled in PWM operation, comprising:
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an electronic system for determining the rotary speed from a measured tracking voltage, which is measured in a turnoff phase; an arrangement for estimating the rotary speed in the PWM phase with the aid of a mathematical model, wherein the rotary speed is ascertained in the PWM phase with the aid of a recursive function
ω
i=ω
i−
1+Δ
ω
, where Δ
ω
=f(Uk,ω
i−
1);and an arrangement for controlling the electrical machine using a control signal, which has a PWM phase in which the electrical machine is periodically switched on and off using a prespecified pulse duty factor, and which has a measuring phase in which the electrical machine is switched off and the tracking voltage is measured. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification