Methods for operating a resolver facility and corresponding resolver facility

Abstract

Resolver device (6) with a resolver (1) comprising at least one receiver winding (3, 4) or at least one excitation winding (2) assigned to / assignable to a rotatably mounted shaft (5), in particular a rotor shaft of an electric machine, and with a device (9) which determines an angular position of the shaft (5) depending on an induced voltage generated by the excitation winding (2) by means of a target excitation signal (SES) with a predefinable frequency and amplitude and detected by the receiver winding (3, 4), wherein means (10) for limiting an electrical voltage on the excitation winding (2) are assigned to the excitation winding (2), wherein the means (10) limit the voltage only above a maximum normal voltage in only one current direction, characterized in that the device (9) increases, in particular doubles, the frequency and / or amplitude of the target excitation signal for a test operation.and has an evaluation device (13) associated with the excitation winding (2), which detects an actual excitation signal (IES) and compares it with the target excitation signal (SES), whereby correct wiring is detected if a positive amplitude of the actual excitation signal (IES) deviates from the target excitation signal (SES), and wherein incorrect wiring is detected if a negative amplitude of the actual excitation signal (IES) deviates from the target excitation signal (SES).

Description

[0001] The invention relates to a resolver device with a resolver comprising at least one receiver winding and at least one excitation winding, which are assigned / assignable to a rotatably mounted shaft, in particular a rotor shaft of an electric machine, and a device which determines a winding position of the shaft depending on an induced voltage generated by the excitation winding by means of a target excitation signal with a predefinable frequency and amplitude, in particular by the device, and detected by the receiver winding.

[0002] Furthermore, the invention relates to a method for operating such a resolver device. State of the art

[0003] To detect the angular position of an electric machine's rotor, a resolver is frequently used, including in the automotive sector. The resolver is an electromagnetic transducer that outputs an electrical quantity, particularly voltage, depending on the rotor's angular position. For this purpose, the resolver typically has a housing containing two receiver windings, offset from each other by 90%, which surround the rotor, which is rotatably mounted within the housing. The rotor also has at least one excitation winding, which is operated with a predefined excitation signal having a predefined frequency and amplitude.Both the excitation winding and the receiver winding can be fixed within the housing or located on the stator side. The excitation winding, through the excitation signal, induces a magnetic field in the rotor or shaft, which in turn induces a voltage in the receiver winding. The coupling into the receiver winding depends on the position of the shaft or rotor, so that the position of the rotor or shaft can be determined by evaluating the signal induced in the receiver winding.

[0004] The resolver is typically connected to a corresponding evaluation unit or control device via a simple plug connection. If the resolver is wired or connected incorrectly, such that the excitation winding connections are reversed, this will result in an inversion of the acquired position information.

[0005] Resolver facilities and procedures for operating them are known from the patent applications JP 2006 - 258 751A, US 2008 / 0 172 202 A1, DE 10 2011 078 586 A1, DE 44 32 520 C1, DE 10 2007 026 786 A1 and US 2004 / 0 150 927 A1. Disclosure of the invention

[0006] The resolver device according to the invention, with the features of claim 1, has the advantage that incorrect wiring, for example, in the sense of reverse polarity of the excitation winding connections, can be reliably detected by simple means. According to the invention, means for limiting the electrical voltage across the excitation winding are provided, wherein the means limit the voltage only above a maximum voltage in only one current direction. By comparing the target excitation signal supplied to the excitation winding with the actual excitation signal, it can then be determined whether the resolver has been wired correctly or incorrectly, in particular whether the excitation winding is connected correctly or incorrectly, i.e., with reversed polarity.The device is expediently designed to increase, in particular double, the excitation frequency and amplitude of the target excitation signal for testing purposes, so that a voltage above the maximum normal voltage is applied to the excitation winding. Depending on the wiring configuration, the actual excitation signal is then influenced by the means such that its amplitude is distorted or shifted relative to the amplitude of the target excitation signal. By comparing the amplitudes, it is thus possible to determine whether the wiring is correct or incorrect.

[0007] Preferably, the device comprises a Zener diode and a diode connected in series with the Zener diode. This allows for simple and cost-effective voltage limiting in only one current direction. Of course, alternative embodiments of the device are also conceivable.

[0008] According to an advantageous further development of the invention, it is further provided that the Zener diode and the diode are connected in parallel to the excitation winding in order to realize the voltage limiting.

[0009] Furthermore, it is planned that an evaluation unit associated with the excitation winding will be provided, which records the actual excitation signal and compares it with the target excitation signal. This will perform the comparison described above.

[0010] Furthermore, the device is designed to double the frequency and / or amplitude of the target excitation signal for test operation, as previously mentioned. Generally, it is advantageous for the device to increase the frequency and / or amplitude of the target excitation signal. However, by simultaneously doubling both amplitude and frequency, the amplitude of the current in the excitation winding's inductance remains unchanged.

[0011] The inventive method with the features of claim 4 is characterized in that, for a test operation, the amplitude and frequency of the target excitation signal are increased, in particular doubled, and that an actual excitation signal of the excitation winding is detected and compared with the target excitation signal in order to detect a correct or incorrect wiring.

[0012] The detection of the wiring is carried out as described above, resulting in the advantages already mentioned.

[0013] Furthermore, it is provided that a correct connection is inferred if the actual excitation signal deviates from the target excitation signal by a positive amplitude, and an incorrect connection is inferred if the actual excitation signal deviates from the target excitation signal by a negative amplitude. In this way, a simple determination of the circuit is possible.

[0014] Furthermore, it is preferably provided that correct or incorrect wiring can be determined based on a time phase during which the voltage at the excitation winding is limited by the means. This allows, alternatively or additionally (for plausibility checks), the detection of whether the excitation winding is correctly or incorrectly connected, for example, to the control unit or a power stage of the control unit. Depending on the time phase, the positive or negative amplitude of the excitation signal can be determined, thus establishing at which amplitude distortion is caused by the voltage limiting means. Accordingly, based on the distortion or the deviation from the target amplitude, correct or incorrect wiring can be determined, as described above. Further features and advantages will become apparent from the above description.

[0015] The invention will now be explained in more detail with reference to the drawing. To this end, we show Fig. 1. A resolver in a simplified representation, Fig. 2 an advantageous resolver device and Fig. 3 excitation signals of an excitation winding of the resolver.

[0016] Fig. Figure 1 shows a simplified representation of a conventional resolver 1 comprising an excitation winding 2, a first receiver winding 3, and a second receiver winding 4. The receiver windings 3 and 4 are arranged around a shaft 5, which is, for example, a rotor shaft of an electric machine, offset from each other by 90°. The shaft 5 is rotatably mounted and can support the excitation winding 2, which can then be electrically contacted, for example, by slip rings and brushes. However, according to the present embodiment, the excitation winding 2 is also fixed to the stator or housing and associated with the rotor in order to inductively couple a magnetic field into the rotor. For this purpose, the excitation winding 2 is operated with an excitation signal of a predetermined amplitude and frequency.

[0017] Shaft 5 is, for example, rotationally fixed to the output shaft of an electric machine, such that the angular position of shaft 5 corresponds to the angular position of the output shaft of the electric machine or the rotor. It is also conceivable that the output shaft of the electric machine directly forms shaft 5.

[0018] During operation, the excitation winding 2 is energized with a target excitation signal using an alternating voltage, which generates a magnetic field in the shaft 5 that is detected by the receiver windings 3 and 4. The phase angle of the voltage induced by the excitation winding 2, as detected by the receiver windings 3 and 4, then depends on the position of the shaft 5. At an angular position of 0°, the magnetic field is most strongly coupled into the cosine track, or receiver winding 3. At an angular position of 90°, the magnetic field is most strongly coupled into the sine track, or receiver winding 4. At an angular position of 45°, the magnetic field is coupled proportionally into receiver windings 3 and 4. During one revolution of the rotor or shaft, the resolver 1 thus delivers a position-modulated alternating voltage to the receiver windings 3 and 4.

[0019] Alternatively, the excitation winding is excited with a sinusoidal alternating voltage. In this case, the amplitudes of the voltages induced in the receiver windings 3 and 4 depend on the angular position of shaft 5 and correspond to the sine and cosine of the angular position of shaft 5.

[0020] The resolver 1 is part of a resolver unit 6, which also includes a device 7 for operating the resolver. The device 7 includes, in particular, a signal generator 8, which, for example, has a voltage source and is electrically connected to the excitation winding 2 via a first connection A1 and a second connection A2. If the connections A1 and A2 are reversed, i.e., if the resolver 1 is connected to the signal generator incorrectly, this leads to an inversion of the determined angle information. With reference to the Fig. 2 and Fig. 3. An advantageous embodiment of the device 7 and a method will now be explained which reliably detect an incorrect wiring of the resolver 1.

[0021] Fig. Figure 2 shows a simplified representation of the resolver device 6 with the signal source 8 and the excitation winding 2. Only one terminal A1 of the signal generator 8 is indicated, and the excitation winding 2 is connected on one side to terminal A1 and on the other side to ground M.

[0022] The resolver device 6 further includes a device 9 that controls the signal source 8 and evaluates the induced voltages detected by the receiver windings 3, 4 in order to determine the angular position of the shaft 5, as previously described.

[0023] The excitation winding 2 is connected to means 10 for limiting the voltage through the excitation winding 2 in one current direction. These means 10 comprise a Zener diode 11 and a diode 12 connected in series in parallel with the excitation winding 2, the Zener diode 11 having a reverse voltage of 12 volts in this embodiment. Furthermore, the excitation winding 2 is connected to an evaluation unit 13, which detects the actual excitation signal of the excitation winding 2 and compares it with the target excitation signal specified by the unit 9. The unit 9 and the evaluation unit 13 can also be combined into a single device, such as a control unit.

[0024] In normal operation, the device 9 controls the resolver device 6 such that a target excitation signal is specified and converted by the excitation winding 2. The voltage induced in the shaft 5 by the excitation signal is coupled into the receiver windings 3, 4 as described previously in order to determine the angular position of the shaft 5. The means 10 are designed such that, in normal operation of the resolver 1, they do not limit the voltage and current through the excitation winding 2 and do not influence or impair the (normal) operation of the resolver.

[0025] To determine the correct wiring of resolver 6 during a test run, device 9 modifies the target excitation signal such that both the amplitude and frequency of the excitation signal are doubled. This simultaneous doubling of amplitude and frequency ensures that the amplitude of the current in the inductor remains unchanged. Preferably, the excitation signal is generated by a suitable electronic circuit, in particular by pulse-width modulation using a microcontroller, for example, in device 9, and preferably filtered to produce a sinusoidal signal. Doubling the amplitude and frequency increases the voltage applied to the excitation winding 2 beyond the maximum normal voltage. The means 10 then act as voltage limiters on the voltage applied to the excitation winding 2.

[0026] Fig.Figure 3 shows a diagram plotted against time t, showing the target excitation signal SES and the actual excitation signal IES. For the first 500 µs, the resolver is driven with the normal target excitation signal. The actual excitation signal corresponds to the specified target excitation signal. After 500 µs, the amplitude and frequency of the target excitation signal are doubled. For a considerable time interval, the actual excitation signal then follows the target excitation signal. However, during the phase in which the mean 10 limits the voltage due to its larger amplitude, the positive amplitude of the actual excitation signal is distorted and deviates from the amplitude of the target excitation signal.

[0027] If the resolver is wired incorrectly, the negative amplitude of the actual excitation signal is distorted. Therefore, by reading back the excitation signal or by capturing the actual excitation signal (ISE), it is easy to determine whether the resolver is wired correctly or incorrectly.

[0028] In operation, the excitation winding 2 is operated at, for example, 20 Vpp (volts peak peak), causing the excitation signal SIN_HI to oscillate between 10 volts and 20 volts, and the excitation signal SIN_LO to oscillate out of phase between 20 volts and 10 volts. In test mode, the amplitude would be increased to 40 Vpp, and preferably the frequency would also be doubled to avoid saturation effects. Subsequently, the excitation signal SIN_HI would oscillate between 5 volts and 25 volts, and the excitation signal SIN_LO would oscillate out of phase between 25 volts and 5 volts. The Zener diode 11, connected in series with the conventional diode 10 between terminal HI and terminal LO of the excitation winding 2, would then become active in phase. This clipping would then be detected by reading back the actual excitation signal as described previously.

Claims

[1] Resolver device (6) with a resolver (1) comprising at least one receiver winding (3, 4) or at least one excitation winding (2) which are assigned / assignable to a rotatably mounted shaft (5), in particular a rotor shaft of an electric machine, and with a device (9) which determines an angular position of the shaft (5) depending on an induced voltage generated by the excitation winding (2) by means of a target excitation signal (SES) with a predefinable frequency and amplitude and detected by the receiver winding (3, 4), wherein means (10) for limiting an electrical voltage on the excitation winding (2) are assigned to the excitation winding (2), wherein the means (10) limit the voltage only above a maximum normal voltage in only one current direction, characterized by, that the device (9) increases, in particular doubles, the frequency and / or amplitude of the target excitation signal for a test operation, and has an evaluation device (13) associated with the excitation winding (2) which detects an actual excitation signal (IES) and compares it with the target excitation signal (SES), whereby correct wiring is detected if a positive amplitude of the actual excitation signal (IES) deviates from the target excitation signal (SES), and wherein incorrect wiring is detected if a negative amplitude of the actual excitation signal (IES) deviates from the target excitation signal (SES). [2] Resolver device (6) according to claim 1, characterized by , that the means (10) has a Zener diode (11) and a diode (12) connected in series with the Zener diode (11). [3] Resolver device (6) according to any one of the preceding claims, characterized by , that the Zener diode (11) and the diode (12) are connected in parallel to the excitation winding (2). [4] Method for operating a resolver device (6) according to any one of the preceding claims, characterized by , that for a test operation the amplitude and / or frequency of the target excitation signal (SES) is increased, in particular doubled, and an actual excitation signal (IES) of the excitation winding (2) is recorded and compared with the target excitation signal in order to detect a correct or incorrect wiring of the resolver device (6), wherein a correct wiring is detected if a positive amplitude of the actual excitation signal (IES) deviates from the target excitation signal (SES), and wherein an incorrect wiring is detected if a negative amplitude of the actual excitation signal (IES) deviates from the target excitation signal (SES). [5] Method according to claim 4, characterized by , that an incorrect or correct connection is detected depending on a time phase in which the voltage is limited by the means (10).

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