DE102019130180A1 - Method for determining an offset of an angular position encoder on a rotor shaft of an electrical synchronous machine with a current or voltage timing offset of an inverter - Google Patents

Abstract

Method (1) for determining an offset of an angular position encoder (101) which is assigned to a rotor of an electrical synchronous machine (100), an inverter which has a controller and an inverter output connected to the electrical synchronous machine (100), comprising the following steps: Setting a first motor speed by means of a first d-inverter voltage and a first q-inverter voltage by the controller, whereby a first d-motor voltage and a first q-motor voltage are generated at the inverter output from the inverter, and setting a first d-inverter current and a first q - Inverter current through the controller, whereby a first d-motor current and a first q-motor current are generated at the inverter output from the inverter; - Setting the first d-motor current and the first q-motor current to zero by the controller by means of a second d-inverter voltage and a second q-inverter voltage; - determining the offset from the second d-inverter voltage, the second n q- inverter voltage and the first motor speed.

Description

The invention relates to a method for determining an offset of an angular position encoder on a rotor shaft of an electrical synchronous machine with a current or voltage timing offset of an inverter.

State of the art

Electric motors as electrical synchronous machines are generally known and are increasingly being used to drive vehicles. An electric motor consists of a stator and a rotor.

The stator comprises a large number of slots in which the windings are guided. The rotor is located in the stator and is connected to a rotor shaft. To control the electrical synchronous machine, it is necessary to know the exact angular position of the rotor in the stator. The position angle can be measured continuously by means of a so-called angular position encoder. The angular position encoder can be attached to the stator or a bearing plate, for example, but must be at a distance from the rotor.

From the DE 10 2011 087 396 A1 a method for mounting an angular position encoder on a rotor shaft of an electric motor is known. Since the physical position is never absolutely precise, the deviation from the built-in position to the desired position must be determined for each electrical machine. This manufacturing-related positional deviation is also called offset. In the method known from DE '396, after the angular position encoder has been installed, the exact position, ie the offset, with respect to the rotor and the angular position encoder attached to the stator is determined on an engine test bench.

The electrical machine is usually operated on converters with pulse width modulation. As a result, there are time delays in the current measurement and also in the voltage output, which are inherent in the system.

When determining the offset, the state of the art is that the motor is accelerated to a speed and then the offset is determined by determining the EMF from the voltages set. There are various boundary conditions to be observed in order to determine the position of the EMF and thus the offset from the voltages.

Task and solution

The object of the present invention is to provide a method for determining an offset of an angular position encoder on a rotor shaft of an electrical synchronous machine with a current or voltage delay of an inverter.

According to the invention, the method for determining an offset of an angular position encoder which is assigned to a rotor of an electrical synchronous machine, an inverter which has a controller and an inverter output connected to the electrical synchronous machine, comprises the following steps: Setting a first motor speed by means of a first d-inverter voltage and a first q-inverter voltage by the regulator, whereby a first d-motor voltage and a first q-motor voltage is generated at the inverter output from the inverter, and setting a first d-inverter current and a first q-inverter current by the regulator, whereby a first d -Motor current and a first q- motor current is generated at the inverter output by the inverter; Setting the first d-motor voltage, the first d-motor current and the first q-motor current to zero by the regulator by means of a second d-inverter voltage and a second q-inverter voltage; Determining the offset from the second d-inverter voltage, the second q-inverter voltage and the first motor speed.

At its inverter output, the inverter provides the alternating voltage and current required for optimal operation of the electrical synchronous machine (d, q motor voltage and d, q motor current). For this purpose, the inverter has a regulator which, as an internal inverter specification, specifies a d and q setpoint value for current and voltage (d, q inverter voltage, d, q inverter current).

The conversion of the 3-phase three-phase field (u, v, w) of an electrical synchronous machine into a d, q coordinate system is among other things among those skilled in the art DE 10 2015 211 863 A1 known. It is therefore clear that a three-phase alternating voltage and current is actually applied to the synchronous electrical machine, which can also be described as d, q motor voltage and current.

The controller also needs information about the position of the rotor in the stator of the electrical synchronous machine. A position sensor on the stator determines the position of the rotor. Due to the manufacturing process, the position sensor has an offset that results from the installation. The controller also needs a certain amount of time to set the voltage and current at the inverter output. This time delay and the production-related offset together form the deviation of the actual position of the rotor from the position on which the regulation is based, i.e. the offset of the angular position encoder. This offset causes the d and q actual values at the inverter output (motor current and motor voltage) to deviate from the setpoint values specified by the controller.

The production-related offset occurs independently of the regulation in the inverter, whereas the time delay depends on the switching frequency of the inverter or the speed of the electrical synchronous machine.

By setting the first d-motor current and the first q-motor current to zero by the controller using a second d-inverter voltage and a second q-inverter voltage, the offset of the angular position encoder can be determined, since it is only dependent on the second d-inverter voltage and the second q inverter voltage.

If there were no offset, the second d-inverter voltage and the second q-inverter voltage would have to be identical to the first d-motor voltage and the first q-motor voltage.

The offset can preferably be determined from the arctangent of the inverse quotient of the second d-inverter voltage and the second q-inverter voltage, the second q-inverter voltage being not equal to zero.

In a further preferred embodiment of the invention, the offset can consist of a hardware offset and a voltage timing offset and include the additional steps: setting a second motor speed, which differs from the first motor speed, by means of a third d-inverter voltage and a third q-inverter voltage through the Regulator, whereby a third d-motor voltage and a third q-motor voltage is generated at the inverter output from the inverter, and setting a third d-inverter current and a third q-inverter current by the regulator, whereby a third d-motor current and a third q-motor current is generated at the inverter output by the inverter; Setting the d-motor current and the q-motor current to zero by the regulator using a fourth d-inverter voltage and a fourth q-inverter voltage; Determining the hardware offset and the voltage timing offset from the second and fourth d-inverter voltage, the second and fourth q-inverter voltage and the first and second motor speed.

The above-mentioned time delay is reflected in a voltage timing offset in the case of a current control, and the production-related offset also mentioned above is known as the hardware offset.

A second speed can be used to determine both the speed-dependent voltage timing offset and the speed-independent hardware offset, since the voltage timing offset increases essentially linearly with the speed. Essentially this means that undesired, technically-related deviations should not be taken into account, e.g. measurement errors.

The offset can preferably consist of a hardware offset and a current timing offset and comprise the additional steps: Setting a fifth d-inverter current and a fifth q-inverter current by the controller with the motor stopped, the fifth q-inverter current being zero, whereby a fifth d- Motor current and a fifth q motor current is generated at the inverter output by the inverter; Determining a fifth d-inverter voltage at the regulator or a fifth d-motor voltage at the inverter output; Setting a third engine speed; Setting, by the controller, a sixth d inverter current and a sixth q inverter current at the third engine speed, the sixth q inverter current being zero; Determining a sixth d-inverter voltage at the regulator or a sixth d-motor voltage at the inverter output, determining the current timing offset from the difference between the fifth and sixth d-inverter voltage at the regulator or the fifth and sixth d-motor voltage at the inverter output.

There is also a time delay when regulating the current, which leads to an angular difference, i.e. a current timing offset, between the motor current vector and the inverter current vector in the d-q coordinate system.

In summary, the offset when regulating the voltage consists of the design-related hardware offset and the time delay in the regulation, i.e. the voltage timing offset, which is also dependent on the speed. The design-related hardware offset is not dependent on the speed.

A special feature is used when calculating the d-motor voltage. If the q-inverter current is zero, the d-motor voltage is independent of the electrical angular frequency of the electrical synchronous machine or the motor speed.

If the q-inverter current is regulated to zero, it can be determined that the d-motor voltage is by no means independent of the angular frequency. The offset can be calculated from this deviation.

In a further embodiment, the engine speed can be in the range of two-thirds of a nominal engine speed.

The first motor speed can preferably be set in a direction of rotation of the electrical synchronous machine opposite to a direction of rotation of the second motor speed.

A plausibility check of the measured values can particularly preferably be carried out as an additional step.

This can be necessary for an ASIL-C, for example.

In a further preferred embodiment of the invention, the method can be carried out as an end of line test of a series production.

According to the invention, an electrical synchronous machine has an angular position encoder and an inverter in which an offset is stored that was determined according to one of the preferred methods.

According to the invention, a vehicle has an electrical synchronous machine, in particular an electric motor, and an inverter in which an offset is stored that was determined according to one of the preferred methods.

Figure list

• 1 shows an inverter with a synchronous electrical machine.
• 2 FIG. 10 shows a method for determining a voltage timing offset and a hardware offset.
• 3rd Figure 11 shows a method for determining a current timing offset.
• 4th shows a combined method for determining a voltage, current timing offset and a hardware offset.
• 5 shows a vehicle with an electrical synchronous machine and an angular position encoder.

In 1 Figure 3 is a schematic representation of an inverter 1 working on an electrical synchronous machine 3rd connected. The synchronous electric machine 3rd , which can be a synchronous motor, for example, has an angular position encoder 7th on, a tachometer is also optional 23 available. Alternatively, the speed can also be determined from the frequency of the voltage in the electrical synchronous machine.

The inverter 1 includes a regulator 5 for controlling the switches 19th , an ammeter at the inverter output 9 , which can optionally also measure voltage. One unity 15th that the readings 21st the voltmeter via a converter 11 to the controller 5 passes on, of course the voltmeter can also be connected directly to the converter 11 be connected.

The converter 11 transforms the three-phase voltages and currents u, v, w measured on the electrical synchronous machine via α and β into the well-known d, q model. To do this, the converter needs 11 the position angle α of the rotor in the electrical synchronous machine 3rd . The one from the angular position encoder 7th measured position angle α _M has an offset. When installing the angular position encoder 7th , which is also called resolver, there is a design-related deviation, a so-called hardware _offset α offset. Furthermore, the inverter 1 as part of its regulation of the electrical synchronous machine 3rd a timing offset in the voltage and current regulation, which depends on the speed (rpm) of the electrical Synchronous machine or the frequency of the voltage or the current is dependent. Since the timing offset depends on the voltage or the current, a voltage _{timing offset α ΔT, u} and a current timing offset α _{ΔT, i result} . _{The position angle α M of} the rotor measured by the angular position encoder must therefore be _{adjusted by the hardware offset α offset and the voltage or current timing offset in} each case as a function of the speed, which leads to a position angle α.

The following describes the determination of the voltage _{timing offset α ΔT, u} and the hardware offset α offset.

The voltage _{timing offset α ΔT, u} as well as the hardware offset α offset can be determined when the inverter _{current i d , Inv} , i _{q, Inv is recorded} on the controller for different speeds, with the _q and d motor currents i d, i q am Inverter output 9 and thus regulated to 0 A in the electrical synchronous machine. The speed is preferably in the middle speed range so that, on the one hand, there is a good resolution of the recording and, on the other hand, iron losses remain negligible. Hardware and voltage timing offset are calculated using the d and q inverter voltages u _{d, Inv} , u _{q, Inv} on the controller 5 certainly.

$${\propto }_{ges,u}={\propto }_{\Delta T,u}+{\propto }_{Offset}$$

It is known that the hardware _offset α offset due to the installation position of the angular position encoder 7th at the rotor is constant over the speed, while the voltage timing _{offsets α ΔT, u} increases proportionally with the frequency, i.e. the speed. The sum of both offsets gives the voltage offset α _{ges, u} for the voltage regulation, i.e. the difference between the voltage u _{d, Inv} , u _{q, Inv} set on the controller and that at the inverter output u _d , u _q , or on the electrical synchronous machine 3rd , so for example voltage applied to a motor also called motor voltage. The converter 11 gets from the angular position encoder 7th communicated the rotor position α _M in the stator and the controller then regulates the switches 19th . Due to the offset α _{offset of} the angular position encoder and the delay of the inverter, for example in the voltage measurement 9 , Converter 11 , Regulator 5 or switch 19th , there is a discrepancy between the desired values of the controller 5 and the one at the inverter output 9 , or in the electrical synchronous machine 3rd concern values. This results in the following equations: $${\propto }_{\Delta T,u}=\Delta T_u\cdot {\omega }_{el}$$

$${\propto }_{Ges,u}={\propto }_{\Delta T,u}+{\propto }_{Offset}$$

As is known to the person skilled in the art, the electrical angular frequency is dependent on the speed of the synchronous machine.

$$u_q={\Psi }_{PM}\cdot {\omega }_{el}$$

Assuming that the motor currents i _d , i _q at the inverter output 9 or in the electrical synchronous machine 3rd are 0 A due to the regulation, apply to the steady-state voltage equations of the synchronous machine 3rd the following equations: $$u_q\stackrel{\text{!}}{=}OV$$

$$u_q={\Psi }_{\mathrm{P.}\mathrm{M.}}\cdot {\omega }_{el}$$

From these equations we get: $$\Delta T_u\cdot {\omega }_{el}=\Delta T_u\cdot \frac{u_q}{{\Psi }_{\mathrm{P.}\mathrm{M.}}}=\frac{\Delta T}{{\Psi }_{\mathrm{P.}\mathrm{M.}}}\cdot u_q$$

As already mentioned, the voltage offset α _{tot, u is} made up of two components. This voltage offset leads to a twist at the inverter output 9 measured voltages u _d , u _q which results in the following: $$\left[\begin{array}{c}{u}_{d,inv}\\ u_{q,\mathrm{I.}nv}\end{array}\right]=\left[\begin{array}{cc}\text{cos}\left({\propto }_{Ges,u}\right)& -\text{sin}\left({\propto }_{Ges,u}\right)\\ \text{sin}\left({\propto }_{Ges,u}\right)& \text{cos}\left({\propto }_{Ges,u}\right)\end{array}\right]\cdot \left[\begin{array}{c}{u}_d\\ u_q\end{array}\right]$$

$$u_{q,inv}=\text{cos}\left(a_{ges,u}\right)\cdot u_q$$

$$\begin{array}{l}\to u_{d,inv}=-\text{sin}\left(a_{ges,u}\right)\cdot \frac{u_{q,Inv}}{\text{cos}\left({\alpha }_{ges,u}\right)}=-\text{tan}{\alpha }_{ges,u}\cdot u_{q,Inv}\\ =-\text{tan}\left(\Delta T_u\cdot {\omega }_{el}+{\alpha }_{Offset}\right)\cdot u_{q,Inv}\end{array}$$

Since the requirement applies that the motor current i _d , i _q in the motor is 0 A, the d motor voltage u _d in the motor must be zero. This results in: $$u_{d,inv}=-\text{sin}\left(a_{Ges,u}\right)\cdot u_q$$

$$u_{q,inv}=\text{cos}\left(a_{Ges,u}\right)\cdot u_q$$

$$\begin{array}{l}\to u_{d,inv}=-\text{sin}\left(a_{Ges,u}\right)\cdot \frac{u_{q,\mathrm{I.}nv}}{\text{cos}\left({\alpha }_{Ges,u}\right)}=-\text{tan}{\alpha }_{Ges,u}\cdot u_{q,\mathrm{I.}nv}\\ =-\text{tan}\left(\Delta T_u\cdot {\omega }_{el}+{\alpha }_{Offset}\right)\cdot u_{q,\mathrm{I.}nv}\end{array}$$

Another transformation leads to: $${\text{tan}}^{-1}\left(-\frac{u_{d,\mathrm{I.}nv}}{u_{q,\mathrm{I.}nv}}\right)=\Delta T_u\cdot {\omega }_{el}+{\alpha }_{Offset}$$

The result can be interpreted as a linear function of ω _el , in which the coefficients represent exactly the desired values voltage _{timing offset α ΔT, u} and hardware offset α offset. $${\text{tan}}^{-1}\left(-\frac{u_{d,\mathrm{I.}nv}}{u_{q,\mathrm{I.}nv}}\right)={\alpha }_{\Delta T,u}\cdot {\omega }_{el}+{\alpha }_{Offset}$$

By means of a series of measurement data that is recorded by a state machine in the corresponding measurement _{mode, the coefficients a ΔT, u} and α _offset can be determined, for example by a least square method.

Advantageously, no q-inverter voltages u _{d, Inv} close to 0 V are used as measured values, since otherwise the coefficient determination could fail.

The determination of the current timing offset α _{ΔT, i is} described below

It should be assumed that the hardware _offset α offset as well as the voltage _{timing offset α ΔT, u have been} compensated. For the current timing, the linear voltage equations are considered in stationary operation: $$\left[\begin{array}{c}{u}_d\\ u_q\end{array}\right]=\left[\begin{array}{cc}{\mathrm{R.}}_s& -{\omega }_{el}{\mathrm{L.}}_q\\ {\omega }_{el}{\mathrm{L.}}_d& {\mathrm{R.}}_s\end{array}\right]\cdot \left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]+\left[\begin{array}{c}0\\ w_{el}{\Psi }_{\mathrm{P.}\mathrm{M.}}\end{array}\right]$$

$$\to u_d=R_S\cdot i_d$$

$$\to u_q={\omega }_{el}{L}_d\cdot i_d+{\varpi }_{el}{\Psi }_{PM}$$

If the q inverter current i _{q, Inv is} regulated to 0 A and the d inverter current i _{d, Inv} to a constant value not equal to 0 A, the following relationship results. It can be seen that for this case the d-motor voltage u _d at the inverter output 9 or in the synchronous machine 3rd is independent of the electrical angular frequency ω _el and thus the speed of the electrical synchronous machine. The current timing offset α _{ΔT, i} can thus be determined by different d motor voltages u _d at different ω _el , that is to say different speeds. $$i_q\stackrel{\text{!}}{=}0\mathrm{A.}$$

$$\to u_d={\mathrm{R.}}_{\mathrm{S.}}\cdot i_d$$

$$\to u_q={\omega }_{el}{\mathrm{L.}}_d\cdot i_d+{\varpi }_{el}{\Psi }_{\mathrm{P.}\mathrm{M.}}$$

The one at the inverter output 9 or on the synchronous machine 3rd applied d- and q-motor current u _d , u _q can only be measured with great effort, with which the controller 5 in the inverter can only adjust its control specifications (q-inverter current i _{q, Inv} to 0 A and d-inverter _{current i d, Inv} constant), which is generated by the invert output 9 to the synchronous machine 3rd However, flowing currents can deviate due to a current timing offset α _{ΔT, i.} This results in a rotation of the d, q motor currents u _d , u _q by the current timing offset α _{ΔT, i,} depending on the timing error ΔT _i and the current electrical angular frequency ω _el, or the speed: $${\propto }_{\Delta T,i}=\Delta T_i\cdot {\varpi }_{el}$$

$$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\text{cos}\left({\propto }_{\Delta T,i}\right)& -\text{sin}\left({\propto }_{\Delta T,i}\right)\\ \text{sin}\left({\propto }_{\Delta T,i}\right)& \text{cos}\left({\propto }_{\Delta T,i}\right)\end{array}\right]\cdot \left[\begin{array}{c}{i}_{d,inv}\\ i_{q,inv}\end{array}\right]$$

This results in the following relationship for the relationship between the motor currents (i _d , i _q ) and the inverter _{currents (i d, Inv} , i _{q, Inv} ): $$\left[\begin{array}{c}{i}_{d,inv}\\ i_{q,\mathrm{I.}nv}\end{array}\right]=\left[\begin{array}{cc}\text{cos}\left({\propto }_{\Delta T,i}\right)& -\text{sin}\left({\propto }_{\Delta T,i}\right)\\ \text{sin}\left({\propto }_{\Delta T,i}\right)& \text{cos}\left({\propto }_{\Delta T,i}\right)\end{array}\right]\cdot \left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]$$

$$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\text{cos}\left({\propto }_{\Delta T,i}\right)& -\text{sin}\left({\propto }_{\Delta T,i}\right)\\ \text{sin}\left({\propto }_{\Delta T,i}\right)& \text{cos}\left({\propto }_{\Delta T,i}\right)\end{array}\right]\cdot \left[\begin{array}{c}{i}_{d,inv}\\ i_{q,inv}\end{array}\right]$$

$$i_q=-\text{sin}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,inv}$$

When the regulator 5 in the inverter 1 regulates the q inverter _{current (i q, Inv} ) to 0 A, the following equation results for the motor currents (i _d , i _q ) at the inverter output 9 , or in the electrical synchronous machine 3rd . $$i_d=\text{cos}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,inv}$$

$$i_q=-\text{sin}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,inv}$$

$$u_d=-R_S\cdot \text{sin}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,Inv}+{\omega }_{el}{L}_q\text{cos}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,Inv}+{\omega }_{el}{\Psi }_{PM}$$

If you now insert these equations into the voltage equations in stationary operation, the following equations result. $$u_d={\mathrm{R.}}_{\mathrm{S.}}\cdot \text{cos}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,\mathrm{I.}nv}+{\omega }_{el}{\mathrm{L.}}_q\text{sin}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,\mathrm{I.}nv}$$

$$u_d=-{\mathrm{R.}}_{\mathrm{S.}}\cdot \text{sin}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,\mathrm{I.}nv}+{\omega }_{el}{\mathrm{L.}}_q\text{cos}\left({\propto }_{\Delta T,i}\right)\cdot i_{d,\mathrm{I.}nv}+{\omega }_{el}{\Psi }_{\mathrm{P.}\mathrm{M.}}$$

After solving the voltage equations for the current timing offset α _{ΔT, i} it can be seen that the angle - and thus also the current timing offset - can only be calculated if the inductances, the permanent flux and the phase resistance of the electrical synchronous machine are known. This is usually not the case.

The current timing offset can be set online, for example, with the aid of a state machine. So while the scheme 5 adjusts pure d-inverter _{current i d, Inv} , the current timing offset α _{ΔT, i is} adjusted until the d-motor voltage u _d at a test speed is identical to the d-motor voltage u _d with a stationary synchronous machine 3rd is there at speed 0 the speed-dependent current timing offset α _{ΔT, i is} not effective. It should be noted that the d-current i _{d inverter, Inv} when the engine is the d-current i _d inverter _Inv is the same for the test speed.

For example, one speed can be adapted. The speed should be as high as possible so that the influence of the current timing offset is great, but not so high that the controller 5 to the Voltage limit or iron losses play a role. The state machine can monitor and readjust the speed so that it remains in a desired band, since a q-motor current flows in the event of a faulty current timing offset and the synchronous machine is decelerated or accelerated.

In reference to 2 is the following one procedure 200 for determining a voltage timing offset of an inverter.

In a first step 201 a positive speed is approached with the electrical synchronous machine and, after the speed has been reached, the d-inverter current i _{d, Inv} and the q-inverter current i _{q, Inv} are regulated to 0A. As a result, the d-motor voltage u _d in the electrical synchronous machine becomes zero. The d, q inverter voltages u _{d, Inv} , u _{q, Inv} regulated by the controller in the inverter are recorded.

The first step 201 is used as the second step 203 repeated at a negative speed. The negative speed is exactly opposite to the direction of rotation of the positive speed. It can make sense that the positive and negative speed are identical for different directions of rotation and only differ in the direction of rotation. However, it is also possible to use a second, positive speed that differs from the first speed. The two values for d, q inverter voltages u _{d, Inv} , u _{q, Inv} are recorded.

In a third step 205 are derived from the recorded values, i.e. the two measuring points for the d, q inverter voltage and the respective speed, or

The angular frequency, the hardware _offset α offset and the voltage _{timing offset α ΔT, u are determined} according to the following formula: $$ta{n}^{-1}\left(-\frac{u_{d,\mathrm{I.}nv}}{u_{q,\mathrm{I.}nv}}\right)={\alpha }_{\Delta T,u}\cdot {\omega }_{el}+{\alpha }_{Offset}$$

In an optional step 207 a plausibility check of the determined hardware _offset α offset and the voltage _{timing offset α ΔT, u is} possible.

• Spannungstiming und Offset: Durch die Einprägung von negativem d-Strom und durch die Drehzahlbeobachtung kann der Offset und die Spannungstimings plausibilisieren werden, da die d-Motorspannung bei Drehzahl gleich der d-Motorspannung im Stillstand sein muss.

The plausibility check can be divided up as follows:

• Voltage timing and offset: The offset and voltage timings can be checked for plausibility by impressing negative d-current and by monitoring the speed, since the d-motor voltage at speed must be the same as the d-motor voltage at standstill.

In reference to 3rd is the following one procedure 300 for determining an offset of an angular position encoder consisting of a current timing offset α _{ΔT, i} and a hardware _offset α offset described, the hardware _offset α offset and the voltage _{timing offset α ΔT, u,} for example, from the method described with reference to 2 is described is known.

In a first step 301 ad motor current i _{d is} impressed when the electrical synchronous machine is at a standstill. When the electrical synchronous machine is at a standstill, there can be no timing offset, i.e. neither voltage nor current timing offset, so that the voltage of the inverter U _{d, Inv is} equal to the d motor voltage u _d .

The rotor in the electrical synchronous machine aligns itself in the d-axis and it is also possible to determine a rough position encoder offset. At the same time, the d motor voltage u _{d is determined} as a later reference.

In a second step 303 the electrical synchronous machine is brought up to speed to the d-inverter current i _{d, Inv} as in the first step 301 memorize. The current timing offset α _{ΔT, i} is set in a third step 305 now changed until the two d-inverter voltages u _{d, inv} from the first and second step 301 , 303 to match. The current timing offset α _{ΔT, i} determined in this way is then stored.

During this variation, the engine must be kept at speed. If necessary, must take the third step 305 canceled if the speed is not reached and repeated when the speed is reached.

In an optional step 307 a plausibility check of the determined current timing offset α _{ΔT, i is} possible.

For this purpose, the synchronous machine can be brought to a higher speed than, for example, two-thirds of the nominal speed. Then a negative d-inverter _{current i d, Inv} , is set on the controller and the speed of the synchronous machine is monitored. The speed should decrease due to the friction. If this is the case, then in step 205 determined current offset can be assumed to be plausible.

In reference to 4th is a combined procedure below 400 for determining an offset α of an angular position encoder consisting of a voltage _{timing offset α ΔT, u} , a current timing offset α _{ΔT, i} and a hardware offset α offset.

The procedure 200 determined in the crotch 205 the hardware _offset α offset and the voltage _{timing offset α ΔT, u} according to the in connection with 2 described formula. The hardware _offset α offset and the voltage timing offset aAT '' can be used in an optional step 207 be checked for plausibility or directly in one step 401 to the next step 301 be handed over. The next steps 301-307 then run as in connection with 3rd described from.

5 Figure 3 is a schematic diagram of one embodiment of a vehicle 100 , for example a hybrid vehicle or an electric vehicle, comprising an electric synchronous machine 3rd , in particular an electric motor to drive the vehicle 100 , with an angular position encoder 7th , its offset by means of the method according to the invention in the inverter 1 is determined.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102011087396 A1 [0004]
• DE 102015211863 A1 [0010]

Claims (10)

Method (1) for determining an offset of an angular position encoder (101) which is assigned to a rotor of an electrical synchronous machine (100), an inverter which has a controller and an inverter output connected to the electrical synchronous machine (100), comprising the following steps: - Setting a first motor speed by means of a first d-inverter voltage and a first q-inverter voltage by the controller, whereby a first d-motor voltage and a first q-motor voltage are generated at the inverter output from the inverter, and Adjusting a first d-inverter current and a first q-inverter current by the controller, thereby generating a first d-motor current and a first q-motor current at the inverter output from the inverter; Setting the first d-motor current and the first q-motor current to zero by the regulator by means of a second d-inverter voltage and a second q-inverter voltage; - Determining the offset from the second d-inverter voltage, the second q-inverter voltage and the first motor speed. Procedure (1) according to Claim 1 , the offset being determined from the arctangent of the inverse quotient of the second d-inverter voltage and the second q-inverter voltage, the second q-inverter voltage being not equal to zero. Method (1) according to one of the preceding claims, wherein the offset consists of a hardware offset and a voltage timing offset, with the additional steps: - Setting a second motor speed, which differs from the first motor speed, by means of a third d-inverter voltage and a third q-inverter voltage by the controller, whereby a third d-motor voltage and a third q-motor voltage are generated at the inverter output from the inverter, and Adjusting a third d-inverter current and a third q-inverter current by the controller, thereby generating a third d-motor current and a third q-motor current at the inverter output from the inverter; Setting the d-motor current and the q-motor current to zero by the regulator by means of a fourth d-inverter voltage and a fourth q-inverter voltage; - Determination of the hardware offset and the voltage timing offset from the second and fourth d-inverter voltage, the second and fourth q-inverter voltage and the first and second motor speed. Method (1) according to one of the preceding claims, wherein the offset consists of a hardware offset and a current timing offset, with the additional steps: - Setting a fifth d-inverter current and a fifth q-inverter current by the controller with the motor stopped, the fifth q-inverter current being zero, whereby a fifth d-motor current and a fifth q-motor current is generated at the inverter output from the inverter; - Determining a fifth d-inverter voltage at the regulator or a fifth d-motor voltage at the inverter output; - setting a third engine speed; Setting the fifth-end inverter current and the sixth q-inverter current by the controller at the third engine speed, the fifth q-inverter current being zero; - determining a sixth d-motor voltage at the inverter output; - Determination of the current timing offset from the difference between the fifth d-inverter voltage at the controller or the fifth d-motor voltage at the inverter output and the sixth d-motor voltage at the inverter output. Method (1) according to one of the preceding claims, wherein the engine speed is in the range of two-thirds of a nominal engine speed. Method (1) according to one of the preceding claims, wherein the first motor speed is set in a direction of rotation of the electrical synchronous machine opposite to a direction of rotation of the second motor speed. Method (1) according to one of the preceding claims, with the additional step: - Plausibility check of the measured values. Method (1) according to one of the preceding claims, wherein the method can be carried out as an end-of-line test of a series production. Electrical synchronous machine (3) with an angular position encoder (7) and an inverter (1) in which a speed-dependent offset that was determined according to one of the previous methods is used. Vehicle (100) with an electrical synchronous machine (3), in particular an electric motor, and an inverter (1) according to FIG Claim 9 .

Images