Method for determining the rotor angle of a synchronous machine and drive for carrying out the method

Abstract

Method for determining the rotor angle of a synchronous machine, in particular using only a single two- or three-component current measurement channel, and drive for carrying out the method, in particular wherein the synchronous machine has a rotor position-dependent stator inductance, wherein an inverter supplies the stator of the synchronous machine with a pulse-width modulated three-phase voltage, which can be characterized for each half of a pulse-width modulation period by a voltage space vector, wherein the motor current is detected and an associated motor current space vector is formed from it, and the voltage space vector is determined at least as a function of this, at least for a respective pulse-width modulation period, wherein the voltage space vector is composed of a component belonging to a fundamental wave component and a component belonging to a carrier signal with a higher frequency compared to the fundamental wave component.wherein the carrier signal is implemented as a periodic signal whose period is an integer multiple of the pulse width modulation period, in particular at least two or three times the pulse width modulation period, wherein the carrier signal is a binary signal, wherein the carrier signal has a pattern that is averaging-free, in particular when averaging over the period of the carrier signal, wherein the carrier signal can be uniquely identified by assigning a voltage value to each half of a pulse width modulation period, wherein the fundamental frequency component of the voltage space vector is constant during the period of the carrier signal, and wherein the current component assigned to the fundamental frequency component and the current component assigned to the carrier signal are determined from the detected current values.

Claims

Method for determining the rotor angle of a synchronous machine, utilizing only a single two- or three-component current measurement channel, wherein the synchronous machine has a circumferentially inhomogeneous rotor inductance and a circumferentially anisotropic stator inductance, wherein an inverter (100) supplies the stator of the synchronous machine with a pulse-width modulated three-phase voltage, which is characterized for each half of a pulse-width modulation period (TPWM) by a voltage space vector, wherein the motor current is detected and a corresponding motor current space vector is formed from it, and the voltage space vector is determined at least as a function of this, at least for each respective pulse-width modulation period (TPWM), wherein the voltage space vector is composed of a component belonging to a fundamental wave component and a component belonging to a carrier signal with a higher frequency compared to the fundamental wave component.characterized in that the carrier signal is implemented as a periodic signal whose period is an integer multiple of the pulse-width modulation (TPWM) period, wherein the period is at least two or three times the pulse-width modulation (TPWM) period, wherein the carrier signal is a binary signal and / or wherein the carrier signal assumes only one of two binary states, which is maintained for at least half a pulse-width modulation (TPWM) period, wherein the carrier signal has a pattern that is averaging-free over the period of the carrier signal, wherein the carrier signal can be uniquely identified by assigning a voltage value to each half of a pulse-width modulation (TPWM) period, and wherein the fundamental frequency component of the voltage space vector is constant during the period of the carrier signal.wherein the current component assigned to the fundamental wave component and the current component assigned to the carrier signal are determined from the recorded current values, wherein the motor current for two motor phases is recorded, wherein no angle sensor is used to record the angular position of the rotor of the synchronous machine, wherein the recorded current values ​​are averaged over a pulse width modulation period and also averaged over each half of a pulse width modulation period (TPWM), wherein a weighting function is used in the averaging process, the temporal profile of which is mirror-symmetric about the midpoint of the interval over which the average is calculated, wherein the weighting function increases monotonically in the first half, i.e., half of the symmetry, of the interval and decreases monotonically in the second half, wherein the pulse width modulation method is a symmetric pulse width modulation method.so that, with the same voltage to be represented, switching processes occur in the first and second halves of the pulse width modulation period, symmetrically to the center of the pulse width modulation period (TPWM), whereby the sign sequence, i.e., the sequence of binary states: (-, -, +, +, +, -, -, +) is used as the pattern, whereby the carrier signal pattern is chosen such that the signal-to-noise ratio is as high as possible when determining the fundamental frequency component and the carrier signal, whereby the pattern is chosen from all possible binary patterns with the same period and the same number of support points within the period such that the signal-to-noise ratio is maximized when determining the parameters that determine the carrier signal and the fundamental frequency component.wherein the binary pattern has a single independent value in each half of the pulse width modulation period and / or the binary pattern can be uniquely represented and / or described by a single state value per pulse width modulation period (TPWM). Method according to claim 1, characterized in that the period of the carrier signal is equal to four times the pulse width modulation period (TPWM). Method according to one of the preceding claims, characterized in that a delta-sigma converter (101, 102, 103) is used for current detection, in particular with subsequent averaging, in particular which generates a data stream whose time average corresponds to the current measurement value and / or corresponds to the current measurement value detected and displayed as an analog value. A method according to one of the preceding claims, characterized in that the output signal of the delta-sigma converter (101, 102, 103) is fed to a means for averaging weighted by a weight function, wherein the average is formed in a time interval corresponding to a pulse width modulation period (TPWM) or half of a pulse width modulation period (TPWM), in particular wherein the weighted average is determined for one pulse width modulation period (TPWM) and also for both halves of the pulse width modulation period (TPWM), in particular wherein the fundamental wave component and / or the superimposed current component is determined from the weighted averages by means of a linear operation. Method according to one of the preceding claims, characterized in that a linear and a quadratic component of the current waveform of the fundamental wave component is taken into account. A method according to one of the preceding claims, characterized in that the temporal discretization of the pattern is selected such that each pulse width modulation (TPWM) period or each half of a pulse width modulation (TPWM) period is assigned a value of the pattern, in particular a single value, and / or that the period duration of the pattern is an integer multiple of a pulse width modulation (TPWM) period or half of a pulse width modulation (TPWM) period. Drive for carrying out a method according to one of the preceding claims, wherein the drive comprises a synchronous machine supplied by an inverter (100), characterized in that the motor current is detected for at least two motor phases, in particular wherein no angle sensor is used to detect the angular position of the rotor of the synchronous machine, wherein the means for current detection comprise a delta-sigma converter (101, 102, 103).

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