Field-oriented control of a permanently excited synchronous reluctance machine

Abstract

For the field-oriented control of a permanently excited synchronous machine with reluctance torque a flux-generating current component and a torque-generating current component are determined as a function of a required torque. A voltage component in the flux direction is determined as a function of the flux-generating current component, and a voltage component perpendicular to the flux direction is determined as a function of the torque-generating current component. Upon determining a differential amount by subtracting a vectorial sum of the voltage components from a maximum voltage a first differential value is obtain, via output from a PI-voltage controller, based on the differential amount. Upon determining an input voltage component based on the flux-generating current component and the first differential value, the permanently excited synchronous machine is controlled based on the input voltage component.

Claims

1. A method for the field-oriented control of a permanently excited synchronous machine with reluctance torque comprising: a) determining a flux-generating current component and a torque-generating current component as a function of a required torque; b) determining (a) a voltage component in a flux direction as a function of the flux-generating current component and (b) a voltage component perpendicular to the flux direction as a function of the torque-generating current component; c) upon determining a differential amount by subtracting a vectorial sum of the voltage components from a maximum voltage, obtaining a first current differential value, via output from a PI-voltage controller, based on the differential amount; d) upon determining an input voltage component based on a sum of the flux-generating current component and the first current differential value, determining an input current component based on the input voltage component; e) determining an achieved torque based on the input current component; f) upon determining a second differential amount by subtracting the achieved torque from the required torque, obtaining a second current differential value, via a PI-torque controller, based on the second differential amount; g) determining a second input voltage component based on a sum of the torque-generating current component and the second current differential value; and h) controlling the permanently excited synchronous machine based on the input voltage component and the second input voltage component.

2. The method of claim 1, further comprising obtaining the flux-generating current component and the torque-generating current component via a first characteristic diagram, wherein the first characteristic diagram is one-dimensional.

3. The method of claim 1, further comprising upon determining a differential by subtracting the input current component from the sum of the flux-generating current component and the first differential value, determining an updated input voltage component based on the differential.

4. The method of claim 3, further comprising determining the updated input voltage component based further on an angular frequency of a rotor or a flux linkage.

5. The method of claim 1, further comprising, upon determining a constant required torque, iteratively determining the input voltage component and the second input voltage component.

6. The method of claim 1, further comprising determining the achieved torque based further on flux linkages.

7. The method of claim 1, wherein the permanently excited synchronous machine is a drive unit of a motor vehicle.

8. A controller for the field-oriented control of a permanently excited synchronous machine with reluctance torque, programmed to: a) determine a flux-generating current component and a torque-generating current component as a function of a required torque; b) determine (a) a voltage component in a flux direction as a function of the flux-generating current component and (b) a voltage component perpendicular to the flux direction as a function of the torque-generating current component; c) upon determining a differential amount by subtracting a vectorial sum of the voltage components from a maximum voltage, obtain a first current differential value, via output from a PI-voltage controller, based on the differential amount; and d) upon determining an input voltage component based on a sum of the flux-generating current component and the first current differential value, determine an input current component based on the input voltage component; e) determine an achieved torque based on the input current component; f) upon determining a second differential amount by subtracting the achieved torque from the required torque, obtain a second current differential value, via a PI-torque controller, based on the second differential amount; g) determine a second input voltage component based on a sum of the torque-generating current component and the second current differential value; and h) control the permanently excited synchronous machine based on the input voltage component and the second input voltage component.

9. The controller of claim 8, wherein the controller is further programmed to obtain the flux-generating current component and the torque-generating current component via a first characteristic diagram, wherein the first characteristic diagram is one-dimensional.

10. The controller of claim 8, wherein the controller is further programmed to, upon determining a differential by subtracting the input current component from the sum of the flux-generating current component and the first differential value, determine an updated input voltage component based on the differential.

11. The controller of claim 10, wherein the controller is further programmed to determine the updated input voltage component based further on an angular frequency of a rotor or a flux linkage.

12. The controller of claim 8, wherein the controller is further programmed to, upon determining a constant required torque, iteratively determine the input voltage component and the second input voltage component.

13. The controller of claim 8, wherein the controller is further programmed to determine the achieved torque based further on flux linkages.

14. The controller of claim 8, wherein the permanently excited synchronous machine is a drive unit of a motor vehicle.

Description

SUMMARY OF THE DRAWINGS

(1) The disclosure and its technical scope are described in greater detail hereinafter with reference to the FIGURE. It should be observed that the exemplary embodiment represented is not intended to limit the disclosure. Specifically, unless explicitly represented otherwise, it is also possible for partial aspects of the subject matter represented in the FIGURE to be extracted and combined with other elements and findings from the present description.

(2) FIG. 1 shows a schematic representation of a motor vehicle having a synchronous machine and a controller, which is specifically configured for the execution of the method described herein.

DESCRIPTION

(3) A motor vehicle 7 is illustrated, having a synchronous machine 1 and a controller 6. The synchronous machine 1 and the controller 6 are connected to a voltage supply 9 and an inverter 15.

(4) The function of the controller 6 is the field-oriented control of the permanently excited synchronous machine 1 with reluctance torque. The controller 6 requires, by way of input variables, a required torque T.sub.ref and a maximum voltage u.sub.max, wherein the controller 6 comprises a PI-voltage controller 2, in which a differential amount from a vectorial sum u.sub.s of the voltage components and the maximum voltage u.sub.max can be processed in order to obtain an output variable Δi.sub.d.

(5) The controller 6 further comprises a PI-torque controller 5, in which a differential amount from the achieved torque 4 and the required torque T.sub.ref can be processed in order to obtain an output variable Δi.sub.q.

(6) The method for the field-oriented control of a permanently excited synchronous machine 1 with reluctance torque comprises, according to step a) determining a flux-generating and a torque-generating current component (i.sub.d,MTPC, i.sub.qMTPC) as a function of a required torque T.sub.ref. According to step b), the method comprises determining a voltage component (u.sub.dref, u.sub.qref) in, and perpendicularly to the flux direction, as a function of the current components (i.sub.d,MTPC, i.sub.qMTPC). In step c), a differential amount is determined from a vectorial sum u.sub.s of the voltage components and a maximum voltage u.sub.max, and is processed in a PI-voltage controller, wherein a first differential value Δi.sub.d is obtained as an output variable. According to step d), the current component i.sub.d,MTPC and the first differential value Δi.sub.d are added, and a voltage component u.sub.d to be input into the synchronous machine 1 is determined. By the addition of the current component i.sub.d,MTPC and the first differential value Δi.sub.d, a current component i.sub.dref is calculated.

(7) The current components i.sub.d,MTPC and i.sub.q,MTPC in step a) are read out respectively from a first characteristic diagram 3, wherein the first characteristic diagram 3 (or the first respective characteristic diagram 3) is one-dimensional (i=f(T.sub.ref)). This signifies that the current components i.sub.d,MTPC and i.sub.q,MTPC entered in the first characteristic diagram 3 are exclusively present as a function of the required torque T.sub.ref. Accordingly, in this case, a first characteristic diagram 3 with a limited number of values is provided, which can be read out in a short time and with a reduced computing capacity.

(8) The current components i.sub.q,MTPC and i.sub.qMTPC are determined as a function of the torque T.sub.ref required (e.g. by a driver of the motor vehicle 7 or by a control device of the motor vehicle 7). The voltage components u.sub.dref and u.sub.qref are determined on this basis.

(9) The new value for the current component i.sub.dref obtained according to step d) is employed for the determination of the voltage component u.sub.d to be input. In the determination of the voltage component u.sub.d to be input, the maximum current converter output voltage 16 can be considered (e.g. by the second controller section 13).

(10) The current component i.sub.d on the synchronous machine proceeds from the voltage component u.sub.d to be input.

(11) The current component i.sub.d can be fed back by means of the controller 6 and subtracted from the current component i.sub.dref. The differential thus obtained can be processed by a first PI-current controller 11 wherein, by way of an output variable, and in consideration of an angular frequency ω of the rotor of the synchronous machine 1, or in consideration of a flux linkage psi.sub.q, the voltage component u.sub.d,ref is determined. In consideration of the saturation behavior of the synchronous machine 1, the voltage component u.sub.d to be input is determined from the voltage component u.sub.dref.

(12) Following step b), in a further step c1), a present torque setting 4 is determined by reference to the voltage components (u.sub.d, u.sub.q) to be input and the attuned current components i.sub.d, i.sub.q). In a further step d1), a differential amount is constituted from the achieved torque 4 and the required torque T.sub.ref, and processed in a PI-torque controller 5. By way of an output variable of the PI-torque controller 5, a second differential value Δi.sub.q is obtained. In a step e1), the current component i.sub.q,MTPC and the differential value Δi.sub.q are added, and a voltage component u.sub.q which is to be input into the synchronous machine is determined.

(13) The new value obtained for the current component i.sub.q according to step e1) is employed for the determination of the voltage component u.sub.q to be input. In the determination of the voltage component u.sub.q to be input, the maximum current converter output voltage 16 can be considered (e.g. by the second controller section 13).

(14) The current component i.sub.q on the synchronous machine 1 proceeds from the voltage component u.sub.q to be input.

(15) The attuned current component i.sub.q can be fed back via the controller 6 and subtracted from the current component i.sub.qref. The differential thus obtained can be processed by a second PI-current controller 12 wherein, by way of an output variable, and in consideration of an angular frequency ω of the rotor of the synchronous machine 1, or in consideration of a flux linkage psi.sub.d, the voltage component u.sub.q,ref is determined. In consideration of the maximum current converter output voltage 16, the voltage component u.sub.q to be input is determined from the voltage component u.sub.q,ref.

(16) Steps c1), d1) and e1) can be executed in parallel with steps c) and d). Steps c) and d), and steps c1), d1) and e1) are executed a number of times in sequence, such that increasingly accurate values for the voltage components (u.sub.d, u.sub.q) and the attuned current components (i.sub.d, i.sub.q) to be input into the synchronous machine can be determined.

(17) The achieved torque 4 is determined in consideration of the input variables psi.sub.d(i.sub.d, i.sub.q) and psi.sub.q(i.sub.d, i.sub.q) for flux linkages and the current components (i.sub.d, i.sub.q) in force on the synchronous machine 1, in the first controller section 10.

(18) As a result of the saturation behavior of the synchronous machine 1, values are dependent upon the current components (i.sub.d, i.sub.q). Values for the flux linkages psi.sub.d(i.sub.d, i.sub.q) and psi.sub.q(i.sub.d, i.sub.q) can be entered in a second characteristic diagram 8.

(19) Further elements of the controller 6 are employed for the known conversion of components which rotate with the rotor (symbols d or q; rotating coordinate system) into stationary components (symbols α and β; stationary coordinate system) and vice versa. Moreover, input of the voltage components u.sub.d and u.sub.q determined further to the above-mentioned conversion is executed by means of a third controller section 14 (pulse-width modulator), by pulse-width modulation (PWM).

LIST OF REFERENCE SYMBOLS

(20) 1 Synchronous machine

(21) 2 PI-voltage controller

(22) 3 First characteristic diagram

(23) 4 Achieved torque

(24) 5 PI-torque controller

(25) 6 Controller

(26) 7 Motor vehicle

(27) 8 Second characteristic diagram

(28) 9 Voltage supply

(29) 10 First controller section

(30) 11 First PI-current controller

(31) 12 Second PI-current controller

(32) 13 Second controller section

(33) 14 Third controller section

(34) 15 Inverter

(35) 16 Maximum current converter output voltage

(36) i.sub.d,MTPC Current component

(37) i.sub.q,MTPC Current component

(38) T.sub.ref Required torque

(39) u.sub.dref Voltage component

(40) u.sub.qref Voltage component

(41) i.sub.dref Current component

(42) i.sub.qref Current component

(43) u.sub.s Vectorial sum

(44) u.sub.max Maximum voltage

(45) Δi.sub.d First differential value

(46) u.sub.d Voltage component

(47) u.sub.q Voltage component

(48) i.sub.d Current component

(49) i.sub.q Current component

(50) Δi.sub.q Second differential value

(51) ω Angular frequency