Sensorless control of salient-pole machines
A controller ( 100 ) for controlling a salient-pole machine ( 200 ) is disclosed. The controller ( 100 ) is adapted to determine at least one operational parameter of the salient-pole machine ( 200 ), such as for example a rotor position, a rotor angle or a steady-state voltage. The controller ( 100 ) comprises a calculating unit for calculating test pulse properties for test pulses for supply to phase inputs of the salient-pole machine. The test pulse properties thereby comprise a pulse width and the calculating unit ( 110 ) is adapted for determining the pulse width in an adaptive manner.
1. A controller for controlling a salient-pole machine, the controller being adapted for determining a steady-state voltage V 0 of phases of the salient-pole machine and comprising
a calculating unit for calculating test pulse properties for test pulses for supply to phase inputs of the salient-pole machine, the test pulse properties comprising a pulse width, wherein the calculating unit is adapted for determining the pulse width in an adaptive manner,
a current response receiving means for receiving a current response in reply to the test voltage pulses supplied to the phases of the salient-pole machine and a processing means for deriving an operational parameter of the salient-pole machine based on the current response,
wherein the calculating unit is adapted for calculating test voltage vectors V 1 , V 2 for consecutive test pulses, each test voltage vector deviating from the steady-state voltage V 0 by a respective voltage deviation ΔV i , ΔV 2 , wherein the test voltage vectors V 1 , V 2 are determined in such a manner that ΔV 1 is at least substantially equal to −ΔV 2 , the controller not requiring an estimation of the induced voltage.
2. A controller according to claim 1 , wherein the controller is adapted for determining the pulse width adaptively as function of the steady state voltage V O .
3. A controller according to claim 1 , wherein the calculating unit is adapted for determining the pulse width of said test pulses based on said calculated test voltage vectors V 1 , V 2 .
4. A controller according to claim 1 , wherein the calculating unit is adapted for calculating test pulses properties taking into account power supply limitations.
5. A controller according to claim 1 , wherein the controller furthermore is adapted for generating a control signal comprising information regarding the test pulses for supply to a pulse generator that is connected with an output to phase inputs of the machine for supplying test pulses to phases of the machine.
6. A controller according to claim 5 , wherein the controller is adapted for adding a zero-sequence component to the calculated control signal.
7. A controller according to claim 1 , wherein the steady-state voltage vector V 0 in a test phase is transformed to a stationary reference frame (αβ) and wherein for a first set of sectors (I, III, IV, VI) in the frame (αβ) a test voltage vector v u+ test is situated on a transverse hexagonal boundary, and for a second set of sectors (II,V) a voltage deviation Δv u test has an amplitude that is determined by a distance of the voltage vector V 0 from an upper or lower horizontal hexagonal boundary.
8. A controller according to claim 1 , wherein the controller is adapted for generating a control signal to a pulse generator comprising a pulse width modulator for controlling the generating of test pulses having a modulated pulse width.
9. A controller according to claim 1 , wherein the controller includes switches arranged to switch the phases between a higher and a lower voltage level, wherein the current responses are received at the current response receiving means after operation of the switches.
10. A controller according to claim 1 , wherein the operational parameter of the salient-pole machine describes a motion state of the salient-pole machine.
11. A controller according to claim 10 , wherein the motion state of the salient-pole machine is expressed in absolute terms with reference to a reference system fixed to the phases of the salient-pole machine.
12. A controller according to claim 1 , wherein the controller is adapted for compensating non-linearity effects in a position estimation of a rotor by using a function that is dependent on a saliency ratio and steady-state current components of the machine.
13. A controller according to claim 1 , wherein the controller furthermore is adapted for adjusting the control of the salient-pole machine based on the determined operational parameter.
14. A controller according to claim 1 , wherein the controller is adapted for deriving an operational parameter based on a difference between two current responses of phases of the salient-pole machine as a result of at least two consecutive test signals having a phase displacement with respect to each other, the controller not requiring a machine model.
15. A controller according to claim 1 , the controller being adapted during operation of the salient-pole machine to perform both the function of estimating a motion state and controlling the salient-pole machine at the same time.
16. A controller according to claim 15 , whereby the test pulses are applied to derive the operational parameter with reduced steady-state current distortion.
17. A controller according to claim 1 , the controller being adapted for controlling a permanent-magnet synchronous machine.
18. A method for controlling a salient-pole machine, the method comprising
determining a steady-state voltage V 0 of phases of the salient-pole machine,
calculating test pulse properties for test pulses for supply to phase inputs of the salient-pole machine, the test pulse properties comprising a pulse width,
wherein calculating test pulse properties comprises determining the pulse width in an adaptive manner,
receiving a current response in reply to the test voltage pulses supplied to the phases of the salient-pole machine and processing the current response for deriving an operational parameter of the salient-pole machine based on the current response,
wherein said calculating comprises calculating test voltage vectors V 1 , V 2 for consecutive test pulses, each test voltage vector deviating from the steady-state voltage V 0 by a respective voltage deviation ΔV 1 , ΔV 2 , wherein the test voltage vectors V 1 , V 2 are determined in such a manner that ΔV 1 is at least substantially equal to −ΔV 2 , said controlling not requiring an estimation of the induced voltage.
19. A method according to claim 18 , wherein the method comprises determining the pulse width adaptively as function of a steady-state voltage V 0 of phases of the salient pole machine.