H-bridge counter-pulse excitation circuit for a resolver

Abstract

An excitation circuit for a transformer-based measuring device is provided, which includes an excitation coil. The excitation circuit comprises an H-bridge and a compensation circuit. The H-bridge converts a unipolar square wave signal into a bipolar square wave signal to drive the excitation coil. The H-bridge includes push-pull amplifiers arranged in two branches. The compensation circuit is coupled between the two branches of the H-bridge and compensates for any distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge.

Description

TECHNOLOGICAL AREA

[0001] The present disclosure relates generally to position sensors and in particular to a position sensor including an excitation circuit for a transformer-based measuring device. BACKGROUND

[0002] A number of transformer-based measuring devices have been developed for detecting the position of an object. One type of transformer-based measuring device is a resolver, which is used to detect angular position. Another type of transformer-based measuring device is a linear variable differential transformer, which is used to detect linear position.

[0003] Specifically, a resolver is a type of electrical device used to detect the angular position of a rotating object, such as a motor shaft. It is a type of rotary transformer that operates by modulating the amplitude of a carrier waveform according to the angular position of the rotating object. Due to its ability to measure angular position, a resolver is ideal for a variety of applications in aerospace, automotive, industrial, medical, and military sectors.

[0004] In aerospace, resolvers are used to determine the position of aircraft control surfaces such as ailerons, flaps, rudders, and elevators. They can also be used to measure the position of engines, propellers, and other components. Resolvers are used in navigation and guidance systems for unmanned aerial vehicles (UAVs) and satellites.

[0005] Besides their use in aerospace, resolvers are used in many other industries. They are used in automotive applications to detect the position of steering wheels, brakes, and transmissions. In industrial applications, they are used to measure the position of conveyor belts, cranes, and other industrial machinery. In medical applications, resolvers are used to measure the position of robotic arms used in surgical procedures.

[0006] Sensors that include a resolver typically incorporate an excitation circuit to drive the resolver's excitation coil, which generates output signals that are picked up by sensing coils and used to determine the angular position. Many conventional resolver excitation circuits include operational amplifiers such as inverting and non-inverting amplifiers. However, if a specific application requires square-wave excitation for the sensor, these excitation circuits can produce a bipolar signal with slightly different positive and negative amplitudes due to the differing characteristics and tolerances of inverting and non-inverting amplifiers. Furthermore, these conventional excitation circuits are often complex and include a large number of components, which can compromise their reliability.

[0007] It would therefore be desirable to have a system and a procedure that take into account at least some of the problems discussed above, as well as other possible problems. SUMMARY

[0008] Exemplary implementations of the present disclosure are directed towards position sensors and, in particular, transformer-based measuring devices (e.g., resolvers or linear variable differential transformers, without limitation) that include an H-bridge push-pull excitation circuit. In this respect, exemplary implementations provide an excitation circuit with an H-bridge circuit that includes push-pull amplifiers arranged in two branches. Push-pull amplifiers are commonly used for capacitive loading; however, in the excitation circuit of exemplary implementations, the push-pull amplifiers are used with an inductive load of the resolver's excitation coil. The excitation circuit may therefore also include a compensation circuit to compensate for any distortion in its output signal caused by the excitation coil acting as an inductive load on the H-bridge circuit.

[0009] The H-bridge circuit, including push-pull amplifiers, can reduce the complexity and number of components in the excitation circuit, which can increase its reliability. The H-bridge circuit can also enable the circuit to generate a bipolar output signal with equal (or substantially equal) positive and negative amplitudes.

[0010] The present disclosure therefore includes, without limitation, the following exemplary implementations.

[0011] Some exemplary implementations provide a position sensor comprising: a transformer-based measuring device that can be connected to a moving object, wherein the transformer-based measuring device includes an excitation coil and a plurality of sensing coils; and an excitation circuit for converting a unipolar square wave signal into a bipolar square wave signal to drive the excitation coil, generate an alternating magnetic field, and induce output signals in the plurality of sensing coils that vary according to the position of the object, wherein the excitation circuit includes: an H-bridge circuit including push-pull amplifiers arranged in two branches, wherein the H-bridge circuit converts the unipolar square wave signal into the bipolar square wave signal;and a compensation circuit coupled between the two branches of the H-bridge circuit, the compensation circuit serving to compensate for any distortion in the bipolar square wave signal caused by the excitation coil as an inductive load on the H-bridge circuit.

[0012] Some exemplary implementations provide an excitation circuit comprising: an H-bridge circuit for converting a unipolar square wave signal into a bipolar square wave signal for driving an excitation coil of a transformer-based measuring device, wherein the H-bridge circuit includes push-pull amplifiers arranged in two branches; and a compensation circuit coupled between the two branches of the H-bridge circuit, wherein the compensation circuit serves to compensate for any distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge circuit.

[0013] Some exemplary implementations provide an excitation circuit comprising: a gate driver circuit for converting a unipolar square wave signal into a bipolar square wave signal for driving an excitation coil of a transformer-based measuring device, wherein the gate driver circuit includes a non-inverting gate driver and an inverting gate driver arranged in two branches to implement an H-bridge circuit; and a compensation circuit coupled between the two branches of the H-bridge circuit, wherein the compensation circuit serves to compensate for any distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge circuit.

[0014] Some exemplary implementations provide a method comprising: converting a unipolar square wave signal into a bipolar square wave signal to drive an excitation coil, wherein the conversion of the unipolar square wave signal includes: applying the unipolar square wave signal to an H-bridge circuit with push-pull amplifiers arranged in two branches, the H-bridge circuit converting the unipolar square wave signal into the bipolar square wave signal; and compensating for the distortion in the bipolar square wave signal caused by the excitation coil as an inductive load on the H-bridge circuit.

[0015] These and other features, aspects, and benefits of the present revelation will become clear upon reading the following detailed description, along with the accompanying figures, which are briefly described below. The present revelation includes any combination of two, three, four, or more features or elements set forth herein, regardless of whether these features or elements are expressly combined or otherwise indicated in a specific exemplary implementation described herein. This revelation is to be understood as a whole, such that all separable features or elements of the revelation, in all its aspects and exemplary implementations, should be considered combinable unless the context of the revelation clearly prescribes otherwise.

[0016] It is understood, therefore, that this summary serves only to outline some exemplary implementations in order to provide a basic understanding of some aspects of revelation. Accordingly, it is understood that the exemplary implementations described above are merely examples and should not be interpreted as limiting the scope of protection or the spirit of revelation in any way. Further exemplary implementations, aspects, and benefits will become clear from the following detailed description in conjunction with the accompanying figures, which exemplify the principles of some of the described exemplary implementations. BRIEF DESCRIPTION OF THE FIGURE(S)

[0017] Having thus described exemplary implementations of the revelation in general, we now refer to the attached figures, which are not necessarily to scale and in which: Fig. 1A a block diagram of a position sensor, including an excitation circuit including an H-bridge circuit with push-pull amplifiers arranged in two branches and a compensation circuit coupled between the two branches, according to some exemplary implementations of the present disclosure; Fig. 1B is a block diagram of a position sensor, which corresponds to the one in Fig. The position sensor shown in 1A is similar and includes a rotor coil, according to some exemplary implementations. Fig. 1C is a block diagram of a position sensor, which corresponds to the one in Fig. 1A resembles the position sensor shown and includes a processing circuit, according to some exemplary implementations; Fig. 2. Unipolar and bipolar rectangular wave signals illustrated according to some exemplary implementations; Fig. Figure 3 illustrates an excitation circuit, which is similar to the excitation circuit of Fig. 1 can correspond, according to some exemplary implementations; Fig. 4 the excitation circuit of Fig. 3 illustrated with a different implementation of the compensation circuit according to some exemplary implementations; Fig. Figure 5 illustrates an excitation circuit, which is similar to the excitation circuit of Fig. 1 can correspond to, in which the H-bridge circuit is embodied by a gate driver circuit, according to some exemplary implementations; Fig. 6 the excitation circuit of Fig. 5 illustrated with a different implementation of the compensation circuit according to some exemplary implementations; Fig. 7, Fig. 8, Fig. 9 and Fig. 10 the excitation circuits of the Fig. 3, Fig. 4, Fig. Figures 5 and 6 illustrate how the excitation circuit includes a voltage follower circuit according to some exemplary implementations; and Fig. 11A and Fig. 11B Flowcharts of a procedure according to various exemplary implementations are shown. DETAILED DESCRIPTION

[0018] Some implementations of the present revelation are now described in more detail below with reference to the accompanying figures, which show some, but not all, implementations of the revelation. Indeed, various implementations of the revelation can be embodied in many different forms and should not be interpreted as limited to those shown herein; rather, these exemplary implementations are provided so that this revelation may be thorough and complete and fully convey to those skilled in the art the scope of the revelation. The same reference signs refer throughout to the same elements.

[0019] Unless otherwise stated or clearly evident from the context, references to first, second, or the like should not be interpreted as implying a particular order. A feature described as being above another feature (unless otherwise stated or clearly evident from the context) may instead be below it, and vice versa; similarly, features described as being to the left of another feature may instead be to its right, and vice versa. Likewise, where reference is made herein to quantitative measures, values, geometric relationships, or the like, unless otherwise stated, one or more, if not all, of these references may be approximate to account for possible acceptable variations, such as those that may occur due to technical tolerances or the like.

[0020] Unless otherwise stated or clearly evident from the context, the "or" used herein to refer to a series of operands is the "inclusive or" and is therefore true if one or more of the operands are true, as opposed to the "exclusive or," which is false if all operands are true. For example, "[A] or [B]" is true if [A] is true, or if [B] is true, or if both [A] and [B] are true. Furthermore, the articles "a" and "an" mean "one or more" unless otherwise stated or unless it is clear from the context that they refer to a singular form. It is also understood that, unless otherwise stated, the terms "data," "content," "digital content," "information," and similar terms may sometimes be used interchangeably.

[0021] Exemplary implementations of the present disclosure relate generally to position sensors and in particular to a position sensor including an excitation circuit for a transformer-based measuring device.

[0022] Fig. Figure 1A is a block diagram of a position sensor 100A for measuring the position of a moving object according to some exemplary implementations of the present disclosure. As shown, the position sensor includes a transformer-based measuring device 102 and an excitation circuit 104. The transformer-based measuring device is connectable to the object 106. The transformer-based measuring device includes an excitation coil 108 and a plurality of sensing coils 110. In some examples, the transformer-based measuring device is a resolver that includes a rotor which can be connected to a shaft (the object 106) that is rotatable. In other examples, the transformer-based measuring device is a linear variable differential transformer (LVDT) that includes a core which can be connected to the object 106, which is linearly movable.

[0023] The excitation circuit 104 can convert a unipolar square wave signal 112 into a bipolar square wave signal 114 to drive the excitation coil 108 of the transformer-based measuring device 102 in order to generate an alternating magnetic field and induce output signals in the plurality of sensor coils 110, which vary depending on the position of the object 106. In the case of a resolver, the output signals can vary depending on the angular position of the rotor and thus of the object 106; and in the case of an LVDT, the output signals can vary depending on the linear position of the core and thus of the object 106.

[0024] In some examples, the excitation circuit 104 includes an H-bridge circuit 116 with push-pull amplifiers 118A, 118B arranged in two branches. The H-bridge circuit can convert the unipolar square wave signal 112 into the bipolar square wave signal 114. As indicated in the summary section, the push-pull amplifiers 118A, 118B of the excitation circuit 104 are used with an inductive load of the excitation coil 108 of the transformer-based measuring device 102. The excitation circuit 104 can therefore also include a compensation circuit 120 to compensate for any distortions in the bipolar square wave signal 114 caused by the excitation coil 108 as an inductive load on the H-bridge circuit 116. In this respect, the compensation circuit can compensate for the inductive current delay in the push-pull amplifiers 118A, 118B.The current delay causes distortion in the bipolar square wave signal 114 due to interactions with the push-pull amplifiers 118A, 118B. In this respect, when the current direction through the push-pull amplifiers 118A, 118B reverses, the voltage drop across the push-pull amplifiers 118A, 118B also reverses; and since the excitation coil 108 is inductive, the current lags the applied voltage. The compensation network can bring the current into phase with the voltage and thereby reduce, if not eliminate, the resulting distortion. In some examples, the compensation circuit can operate in resonance with the excitation coil; and in these examples, the compensation circuit can be called a resonant compensation circuit.

[0025] An example of a suitable unipolar square wave signal 112 is a pulse width modulation (PWM) signal which can be provided with a duty cycle of 50%. Fig. Figure 2 further illustrates the unipolar square wave signal 112 and the bipolar square wave signal 114, wherein the bipolar square wave signal 114 can be amplified relative to the unipolar square wave signal 112. In some examples, the bipolar square wave signal 114 includes pulses whose amplitude alternates between a first supply rail and a second supply rail. As also shown, in some examples the bipolar square wave signal can be output as a differential signal pair 216A, 216B for input at the respective ends of the excitation coil 108 of the transformer-based measuring device 102.

[0026] Again with reference to Fig. 1A The excitation coil 108 can be driven to generate an alternating magnetic field and induce output signals in the plurality of sensor coils 110, which vary depending on the position of the object 106. In this respect, the excitation coil 108 can be magnetically coupled to the sensing coils 110. In some configurations of the transformer-based measuring device 102, such as in the case of an LVDT that encloses a core, the core can be ferromagnetic and the excitation coil can be magnetically coupled to the sensing coils via the ferromagnetic core.

[0027] In some configurations of the transformer-based measuring device 102, such as in the case of a resolver that includes a rotor, the excitation coil 108 can be located on the rotor and the plurality of sensing coils 110 can be stationary relative to the rotor, which moves with the object 106 (e.g., in a resolver, the plurality of sensing coils 110 can be located on a stator in which the rotor rotates). In other configurations, such as in Fig. Figure 1B shows a position sensor 100B. The transformer-based measuring device 102 can include a rotor coil 122, and the excitation coil 108 and the plurality of sensing coils 110 can all be stationary relative to the rotor coil 122 (e.g., located on the stator). The excitation coil 108 can be magnetically coupled to the sensing coils 110 via the rotor coil 122. The alternating magnetic field generated by the excitation coil 108 can therefore induce a current in the rotor coil 122, which generates a secondary alternating magnetic field and induces the output signals in the plurality of sensing coils 110.

[0028] Fig. 1C is a block diagram of a 100C position sensor, which corresponds to the one in Fig. The position sensor 100A shown in Figure 1A is similar and includes a processing circuit 124, according to some exemplary implementations. In some examples, the processing circuit 124 can process the output signals from the plurality of sensing coils 110 to determine the position of the object 106 to which the transformer-based measuring device 102 can be connected. In various examples, the processing circuit 124 can include, without limitation, a demodulation circuit, a signal conditioning circuit, or analog-to-digital converters (ADCs). The processing circuit 124 can also include, without limitation, a general-purpose or specialized processor, microprocessor, controller, or microcontroller.

[0029] Fig. Figure 3 illustrates an excitation circuit 300, which corresponds to the excitation circuit 104 of Fig. 1 can correspond to, according to some exemplary implementations. As shown, the unipolar square wave signal 112 can be a first unipolar square wave signal 302, and the excitation circuit 300 can include a polarity inverter 304 to convert the first unipolar square wave signal 302 into a second unipolar square wave signal 306, which has a polarity opposite to the first unipolar square wave signal 302. The excitation circuit 300 can optionally also include a buffer at an input to the H-bridge circuit 308 to adjust the timing, i.e., the phase, between the first unipolar square wave signal 302 and the second unipolar square wave signal 306.

[0030] As also shown, the excitation circuit 300 includes an H-bridge circuit 308 for converting the first unipolar square wave signal 302 and the second unipolar square wave signal 306 into a bipolar square wave signal 114 to drive the excitation coil 108 of the transformer-based measuring device 102 (not shown). The H-bridge circuit 308 can include a first push-pull amplifier 310A and a second push-pull amplifier 310B arranged in two branches. The first push-pull amplifier 310A can be driven by the first unipolar square wave signal 302, and the second push-pull amplifier 310B can be driven by the second unipolar square wave signal 306. The excitation circuit 300 can also include a compensation circuit 312 coupled between the two branches of the H-bridge circuit 308.In this respect, the compensation circuit 312 can compensate for any distortions in the bipolar square wave signal 114 caused by the excitation coil 108 as an inductive load on the H-bridge circuit 308.

[0031] In some examples, the first push-pull amplifier 310A and the second push-pull amplifier 310B each include a complementary transistor pair connected in a push-pull configuration. The gates of the complementary transistor pair of the first push-pull amplifier 310A are driven by the first unipolar square wave signal 302, and the gates of the complementary transistor pair of the second push-pull amplifier 310B are driven by the second unipolar square wave signal 306. The first push-pull amplifier 310A and the second push-pull amplifier 310B can output respective signals from the differential signal pair 216A and 216B to form a bipolar square wave signal 114.

[0032] As some more concrete examples show, the first push-pull amplifier 310A includes a complementary transistor pair M 31 , M 32 The first and second push-pull amplifier 310B form a complementary transistor pair M 33 , M 34 The complementary transistor pair for the first and second push-pull amplifiers 310A and 310B includes a respective high-side transistor M. 31 / M 33 for coupling the excitation coil to a first supply rail Vcc and a respective low-side transistor M 32 / M 34 to couple the excitation coil to a second supply rail, designated GND. The complementary transistor pair can consist of any number of different transistor types. In the illustrated example, the transistors are metal-oxide-semiconductor field-effect transistors (MOSFETs). In particular, the respective high-side transistors M31 / M 33 a p-type MOSFET and the respective low-side transistors M 32 / M 34 an n-type MOSFET.

[0033] In some examples, the compensation circuit includes a first compensation circuit R. 31 , C 31 , which is coupled to an output of the first push-pull amplifier 310A, and a second compensation circuit R 32 , C 32 , which is coupled to the output of the second push-pull amplifier 206B. In the shown, non-restrictive example, one end of the resistor R is 31 coupled to the output of the first push-pull amplifier 310A and a second terminating resistor R 31 via capacitor C 31 coupled to the second supply rail, GND. Similarly, one end of the resistor R 32 coupled to the output of the second push-pull amplifier 310B and a second terminating resistor R 32 via capacitor C32 coupled to the second supply rail, GND. Thus, the first compensation circuit R 31 , C 31 and the second compensation circuit R 32 , C 32 coupled via the second supply rail between the two branches of the H-bridge circuit 308. In other examples, such as in Fig. As shown in Figure 4, the compensation circuit comprises 408 R. 41 , C 41 , which are coupled between the outputs of the first push-pull amplifier 310A and the second push-pull amplifier 310B. In the non-restrictive, in Fig. The 4 examples shown are the resistor R 41 and the capacitor C 41The compensation circuit 408 is connected in series between the outputs of the first push-pull amplifier 310A and the second push-pull amplifier 310B. It is shown as a resistor-capacitor circuit (RC circuit). However, it should be clear that the compensation circuit 408 can be implemented in a number of different ways.

[0034] In some examples, the polarity inverter 304 and the H-bridge circuit 308 are embodied by a gate driver circuit including a non-inverting gate driver that includes the first push-pull amplifier 310A, and an inverting gate driver that includes the polarity inverter and the second push-pull amplifier 310B. In some of these examples, the gate driver circuit can output the bipolar square wave signal 114 as the differential signal pair 216A, 216B, which are output by the respective non-inverting and inverting gate drivers of the gate driver circuit.

[0035] Fig. 5 and Fig. Figure 6 illustrates examples in which the excitation circuit includes a gate driver circuit 504 with a non-inverting gate driver 506A and an inverting gate driver 506B, each outputting the differential signal pair 216A, 216B. Some examples of a suitable gate driver circuit are the following power MOSFET drivers from Microchip Technology Inc. of Chandler, Arizona, all of which include a non-inverting gate driver and an inverting gate driver: TC4425A, TC4428A, MIC4425, MIC4128, MIC4428, MCP14E8, MCP14A0305, MCP14E5, MCP14E5, MCP14A0455, MCP1405A, and MCP4225. Other examples of a suitable gate driver circuit include those from Microchip Technology Inc.available power MOSFET drivers TC1412N and MCP14A0152, which include a non-inverting gate driver, as well as the power MOSFET drivers TC1412 and MCP14A0151, which include an inverting gate driver and are also available from Microchip Technology Inc.

[0036] In some examples, the excitation circuit 104 includes a voltage buffer, such as a voltage follower circuit for transmitting the bipolar square wave signal 114 from the H-bridge circuit 116 to the compensation circuit 120. Fig. 7 and Fig. 8 includes, for example, a voltage follower circuit 720 for transmitting the bipolar square wave signal from the H-bridge circuit 308 to the compensation circuit 312 or 408. In Fig. 9 and Fig. 10 includes, for example, the excitation circuit the voltage follower circuit 720 for transmitting the bipolar square wave signal from the gate driver circuit 504 to the compensation circuit 508, 608.

[0037] In Fig. According to some examples, the voltage follower circuit 720 includes a transistor and diode pair for each of the first and second push-pull amplifiers 310A, 310B ( Fig. 7 and Fig. 8) or of the non-inverting and inverting gate drivers 506A, 506B ( Fig. 9 and Fig. 10). In particular, the voltage follower circuit includes 720 transistors M 71 , M 72 and breakdown diodes D 71 , D 72 for the first push-pull amplifier 310A / non-inverting gate driver 506A and transistors M 73 , M 74 and breakdown diodes D 73 , D 74The second push-pull amplifier is a 310B / non-inverting gate driver, and the transistors are implemented using bipolar junction transistors (BJTs). However, it should be clear that the voltage follower circuit can be implemented in a number of different ways.

[0038] Fig. 11A and Fig. Figure 11B contains flowcharts of a method 1100 according to various exemplary implementations. The method includes the conversion of a unipolar square wave signal into a bipolar square wave signal for driving an excitation coil, as described in Block 1102 of Fig. 11A shown, one.

[0039] The conversion of the unipolar square wave signal involves applying the unipolar square wave signal to an H-bridge circuit with push-pull amplifiers arranged in two branches, wherein the H-bridge circuit converts the unipolar square wave signal into the bipolar square wave signal, as shown in Block 1104. The conversion of the unipolar square wave signal also includes compensating for the distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge circuit, as shown in Block 1106.

[0040] In some examples, the excitation coil is part of a transformer-based measuring device connected to a moving object and including a plurality of sensing coils. The bipolar square-wave signal drives the excitation coil to generate an alternating magnetic field and induce output signals in the plurality of sensing coils that vary depending on the object's position. In some of these examples, Method 1100 includes processing the output signals to determine the object's position, as described in Block 1108 of Fig. 11B is shown.

[0041] In some examples, the unipolar square wave signal is a first unipolar square wave signal, and the conversion of the unipolar square wave signal at block 1102 involves converting the first unipolar square wave signal into a second unipolar square wave signal that has the opposite polarity to the first unipolar square wave signal. In some of these examples, the push-pull amplifiers include a first push-pull amplifier driven by the first unipolar square wave signal and a second push-pull amplifier driven by the second unipolar square wave signal.

[0042] In some examples where the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, the distortion at block 1106 is compensated using a first compensation circuit coupled to an output of the first push-pull amplifier and a second compensation circuit coupled to the output of the second push-pull amplifier.

[0043] In some examples where the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, the distortion at block 1106 is compensated using a compensation circuit coupled between the outputs of the first push-pull amplifier and the second push-pull amplifier.

[0044] In some examples, the distortion at block 1106 is compensated using a resistor-capacitor circuit (RC circuit).

[0045] As explained above and repeated below, the present disclosure includes, without limitation, the following exemplary implementations.

[0046] Clause 1. A position sensor comprising: a transformer-based measuring device that can be connected to a moving object, wherein the transformer-based measuring device includes an excitation coil and a plurality of sensing coils; and an excitation circuit for converting a unipolar square wave signal into a bipolar square wave signal in order to drive the excitation coil, generate an alternating magnetic field and induce output signals in the plurality of sensing coils that vary according to the position of the object, wherein the excitation circuit includes: an H-bridge circuit including push-pull amplifiers arranged in two branches, wherein the H-bridge circuit converts the unipolar square wave signal into the bipolar square wave signal;and a compensation circuit coupled between the two branches of the H-bridge circuit, the compensation circuit serving to compensate for any distortion in the bipolar square wave signal caused by the excitation coil as an inductive load on the H-bridge circuit.

[0047] Clause 2. The position sensor according to Clause 1, wherein the position sensor comprises a processing circuit to process the output signals in order to determine the position of the object.

[0048] Clause 3. The position sensor according to Clause 1 or Clause 2, wherein the transformer-based measuring device is a resolver, the object to which the transformer-based measuring device can be connected is a rotatable shaft, and the output signals in the plurality of sensing coils vary according to an angular position of the shaft.

[0049] Clause 4. The position sensor according to any one of Clauses 1 to 3, wherein the transformer-based measuring device is a linear variable differential transformer (LVDT) in which the object to which the transformer-based measuring device can be connected is linearly movable and the output signals in the plurality of sensing coils vary according to a linear position of the object.

[0050] Clause 5. The position sensor according to any of Clauses 1 to 4, wherein the bipolar square wave signal includes pulses whose amplitude alternates between a first supply rail and a second supply rail.

[0051] Clause 6. The position sensor according to one of Clauses 1 to 5, wherein each of the push-pull amplifiers includes a complementary pair of transistors connected in a push-pull configuration.

[0052] Clause 7. The position sensor according to any one of Clauses 1 to 6, wherein the unipolar square wave signal is a first unipolar square wave signal and the excitation circuit includes a polarity inverter to convert the first unipolar square wave signal into a second unipolar square wave signal having the opposite polarity to the first unipolar square wave signal, and wherein the push-pull amplifiers include a first push-pull amplifier driven by the first unipolar square wave signal and a second push-pull amplifier driven by the second unipolar square wave signal.

[0053] Clause 8. The position sensor according to Clause 7, wherein each of the first push-pull amplifier and the second push-pull amplifier includes a complementary pair of transistors connected in a push-pull configuration.

[0054] Clause 9. The position sensor according to Clause 8, wherein gates of the complementary transistor pair of the first push-pull amplifier are driven by the first unipolar square wave signal and the gates of the complementary transistor pair of the second push-pull amplifier are driven by the second unipolar square wave signal.

[0055] Clause 10. The position sensor according to Clause 8 or Clause 9, wherein the complementary transistor pair includes a high-side transistor for coupling the excitation coil to a first supply rail and a low-side transistor for coupling the excitation coil to a second supply rail.

[0056] Clause 11. The position sensor according to one of clauses 1 to 10, wherein the H-bridge circuit is to output the bipolar square wave signal as a differential signal pair for input at the respective ends of the excitation coil.

[0057] Clause 12. The position sensor according to Clause 11, wherein the push-pull amplifiers output each of the differential signal pair.

[0058] Clause 13. The position sensor according to any one of Clauses 1 to 12, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the compensation circuit includes a first compensation circuit coupled to an output of the first push-pull amplifier and a second compensation circuit coupled to the output of the second push-pull amplifier.

[0059] Clause 14. The position sensor according to any one of Clauses 1 to 13, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier and wherein the compensation circuit is coupled between the outputs of the first push-pull amplifier and the second push-pull amplifier.

[0060] Clause 15. The position sensor according to any of Clauses 1 to 14, wherein the excitation circuit includes a voltage buffer to transfer the bipolar square wave signal from the H-bridge circuit to the compensation circuit.

[0061] Clause 16. The position sensor according to Clause 15, wherein the voltage buffer is a voltage follower circuit.

[0062] Clause 17. The position sensor according to any one of Clauses 1 to 16, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the H-bridge circuit is embodied by a gate driver circuit including a non-inverting gate driver including the first push-pull amplifier and an inverting gate driver including the second push-pull amplifier.

[0063] Clause 18. The position sensor according to Clause 17, wherein the gate driver circuit is to output the bipolar square wave signal as a differential signal pair, which is output by the respective non-inverting gate driver and the inverting gate driver.

[0064] Clause 19. The position sensor according to any of Clauses 1 to 18, wherein the compensation circuit is a resistor-capacitor circuit (RC circuit).

[0065] Clause 20. An excitation circuit comprising: an H-bridge circuit for converting a unipolar square wave signal into a bipolar square wave signal for driving an excitation coil of a transformer-based measuring device, wherein the H-bridge circuit includes push-pull amplifiers arranged in two branches; and a compensation circuit coupled between the two branches of the H-bridge circuit, wherein the compensation circuit serves to compensate for any distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge circuit.

[0066] Clause 21. The excitation circuit according to Clause 20, wherein the transformer-based measuring device is a resolver.

[0067] Clause 22. The excitation circuit according to Clause 20 or Clause 21, wherein the transformer-based measuring device is a linear variable differential transformer (LVDT).

[0068] Clause 23. The excitation circuit according to one of clauses 20 to 22, wherein the bipolar square wave signal includes pulses whose amplitude alternates between a first supply rail and a second supply rail.

[0069] Clause 24. The excitation circuit according to one of clauses 20 to 23, wherein each of the push-pull amplifiers includes a complementary pair of transistors connected in a push-pull configuration.

[0070] Clause 25. The excitation circuit according to any one of Clauses 20 to 24, wherein the unipolar square wave signal is a first unipolar square wave signal and the excitation circuit includes a polarity inverter to convert the first unipolar square wave signal into a second unipolar square wave signal having the opposite polarity to the first unipolar square wave signal, and wherein the push-pull amplifiers include a first push-pull amplifier driven by the first unipolar square wave signal and a second push-pull amplifier driven by the second unipolar square wave signal.

[0071] Clause 26. The excitation circuit according to Clause 25, wherein each of the first push-pull amplifier and the second push-pull amplifier includes a complementary pair of transistors connected in a push-pull configuration.

[0072] Clause 27. The excitation circuit according to Clause 26, wherein gates of the complementary transistor pair of the first push-pull amplifier are driven by the first unipolar square wave signal and the gates of the complementary transistor pair of the second push-pull amplifier are driven by the second unipolar square wave signal.

[0073] Clause 28. The excitation circuit according to Clause 26 or Clause 27, wherein the complementary transistor pair includes a high-side transistor for coupling the excitation coil to a first supply rail and a low-side transistor for coupling the excitation coil to a second supply rail.

[0074] Clause 29. The excitation circuit according to one of clauses 20 to 28, wherein the H-bridge circuit is to output the bipolar square wave signal as a differential signal pair for input at the respective ends of the excitation coil.

[0075] Clause 30. The excitation circuit according to Clause 29, wherein the push-pull amplifiers output each of the differential signal pair.

[0076] Clause 31. The excitation circuit according to any of clauses 20 to 30, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the compensation circuit includes a first compensation circuit coupled to an output of the first push-pull amplifier and a second compensation circuit coupled to the output of the second push-pull amplifier.

[0077] Clause 32. The excitation circuit according to one of clauses 20 to 31, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier and wherein the compensation circuit is coupled between the outputs of the first push-pull amplifier and the second push-pull amplifier.

[0078] Clause 33. The excitation circuit according to one of Clauses 20 to 32, wherein the excitation circuit includes a voltage buffer to transfer the bipolar square wave signal from the H-bridge circuit to the compensation circuit.

[0079] Clause 34. The excitation circuit according to Clause 33, wherein the voltage buffer is a voltage follower circuit.

[0080] Clause 35. The excitation circuit according to any of Clauses 20 to 34, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the H-bridge circuit is embodied by a gate driver circuit including a non-inverting gate driver including the first push-pull amplifier and an inverting gate driver including the second push-pull amplifier.

[0081] Clause 36. The excitation circuit according to Clause 35, wherein the gate driver circuit is to output the bipolar square wave signal as a differential signal pair, which is output by the respective non-inverting gate driver and the inverting gate driver.

[0082] Clause 37. The excitation circuit according to one of clauses 20 to 36, wherein the compensation circuit is a resistor-capacitor circuit (RC circuit).

[0083] Clause 38. An excitation circuit comprising: a gate driver circuit for converting a unipolar square wave signal into a bipolar square wave signal for driving an excitation coil of a transformer-based measuring device, wherein the gate driver circuit includes a non-inverting gate driver and an inverting gate driver arranged in two branches to implement an H-bridge circuit; and a compensation circuit coupled between the two branches of the H-bridge circuit, wherein the compensation circuit serves to compensate for any distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge circuit.

[0084] Clause 39. The excitation circuit according to Clause 38, wherein the bipolar square wave signal includes pulses whose amplitude alternates between a first supply rail and a second supply rail.

[0085] Clause 40. The excitation circuit according to Clause 38 or Clause 39, wherein the gate driver circuit is to output the bipolar square wave signal as a differential signal pair, which is output by the respective non-inverting gate driver and the inverting gate driver.

[0086] Clause 41. The excitation circuit according to one of Clauses 38 to 40, wherein the non-inverting gate driver includes a first push-pull amplifier and the inverting gate driver includes a polarity inverter and a second push-pull amplifier.

[0087] Clause 42. The excitation circuit according to Clause 41, wherein the unipolar square wave signal is a first unipolar square wave signal and the polarity inverter is to convert the first unipolar square wave signal into a second unipolar square wave signal which has the opposite polarity to the first unipolar square wave signal, and wherein the first push-pull amplifier is driven by the first unipolar square wave signal and the second push-pull amplifier is driven by the second unipolar square wave signal.

[0088] Clause 43. The excitation circuit according to Clause 41 or Clause 42, wherein each of the first push-pull amplifier and the second push-pull amplifier includes a complementary pair of transistors connected in a push-pull configuration.

[0089] Clause 44. The excitation circuit according to Clause 43, wherein gates of the complementary transistor pair of the first push-pull amplifier are driven by the first unipolar square wave signal and the gates of the complementary transistor pair of the second push-pull amplifier are driven by the second unipolar square wave signal.

[0090] Clause 45. The excitation circuit according to Clause 43 or Clause 44, wherein the complementary transistor pair includes a high-side transistor for coupling the excitation coil to a first supply rail and a low-side transistor for coupling the excitation coil to a second supply rail.

[0091] Clause 46. The excitation circuit according to one of clauses 38 to 45, wherein the H-bridge circuit is to output the bipolar square wave signal as a differential signal pair for input at the respective ends of the excitation coil.

[0092] Clause 47. The excitation circuit according to Clause 46, wherein the non-inverting gate driver and the inverting gate driver are to output each of the differential signal pairs.

[0093] Clause 48. The excitation circuit according to any one of Clauses 38 to 47, wherein the compensation circuit includes a first compensation circuit coupled to an output of the non-inverting gate driver and a second compensation circuit coupled to the output of the inverting gate driver.

[0094] Clause 49. The excitation circuit according to one of clauses 38 to 48, wherein the compensation circuit is coupled between outputs of the non-inverting gate driver and the inverting gate driver.

[0095] Clause 50. The excitation circuit according to one of Clauses 38 to 49, wherein the excitation circuit includes a voltage buffer to transfer the bipolar square wave signal from the H-bridge circuit to the compensation circuit.

[0096] Clause 51. The excitation circuit according to Clause 50, wherein the voltage buffer is a voltage follower circuit.

[0097] Clause 52. The excitation circuit according to one of clauses 38 to 51, wherein the compensation circuit is a resistor-capacitor circuit (RC circuit).

[0098] Clause 53. A method comprising: converting a unipolar square wave signal into a bipolar square wave signal for driving an excitation coil, wherein the conversion of the unipolar square wave signal includes: applying the unipolar square wave signal to an H-bridge circuit with push-pull amplifiers arranged in two branches, the H-bridge circuit converting the unipolar square wave signal into the bipolar square wave signal; and compensating for the distortion in the bipolar square wave signal caused by the excitation coil as an inductive load on the H-bridge circuit.

[0099] Clause 54. The method according to Clause 53, wherein the excitation coil belongs to a transformer-based measuring device connected to a moving object and including a plurality of sensing coils, wherein the bipolar square wave signal drives the excitation coil to generate an alternating magnetic field and to induce output signals in the plurality of sensing coils which vary according to a position of the object, and wherein the method includes processing the output signals to determine the position of the object.

[0100] Clause 55. Method according to Clause 54, wherein the transformer-based measuring device is a resolver, the object to which the transformer-based measuring device is connected is a rotating shaft, and the output signals in the plurality of sensing coils vary according to an angular position of the shaft.

[0101] Clause 56. Method according to Clause 54 or Clause 55, wherein the transformer-based measuring device is a linear variable differential transformer (LVDT) in which the object to which the transformer-based measuring device is connected moves linearly and the output signals in the plurality of sensing coils vary according to a linear position of the object.

[0102] Clause 57. The method according to one of Clauses 53 to 56, wherein the bipolar square wave signal includes pulses whose amplitude alternates between a first supply rail and a second supply rail.

[0103] Clause 58. The method according to one of Clauses 53 to 57, wherein each of the push-pull amplifiers includes a complementary pair of transistors connected in a push-pull configuration.

[0104] Clause 59. The method according to any one of Clauses 53 to 58, wherein the unipolar square wave signal is a first unipolar square wave signal and the conversion of the unipolar square wave signal includes converting the first unipolar square wave signal into a second unipolar square wave signal having the opposite polarity to the first unipolar square wave signal, and wherein the push-pull amplifiers include a first push-pull amplifier driven by the first unipolar square wave signal and a second push-pull amplifier driven by the second unipolar square wave signal.

[0105] Clause 60. The method according to Clause 59, wherein each of the first push-pull amplifier and the second push-pull amplifier includes a complementary pair of transistors connected in a push-pull configuration.

[0106] Clause 61. The method according to Clause 60, wherein gates of the complementary transistor pair of the first push-pull amplifier are driven by the first unipolar square wave signal and the gates of the complementary transistor pair of the second push-pull amplifier are driven by the second unipolar square wave signal.

[0107] Clause 62. The method according to Clause 60 or Clause 61, wherein the complementary transistor pair includes a high-side transistor for coupling the excitation coil to a first supply rail and a low-side transistor for coupling the excitation coil to a second supply rail.

[0108] Clause 63. The method according to one of Clauses 53 to 62, wherein the H-bridge circuit outputs the bipolar square wave signal as a differential signal pair for input at the respective ends of the excitation coil.

[0109] Clause 64. The method according to Clause 63, wherein the push-pull amplifiers output each of the differential signal pair.

[0110] Clause 65. The method according to any one of Clauses 53 to 64, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the distortion is compensated using a first compensation circuit coupled to an output of the first push-pull amplifier and a second compensation circuit coupled to the output of the second push-pull amplifier.

[0111] Clause 66. The method according to any one of Clauses 53 to 65, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier and wherein the distortion is compensated using a compensation circuit coupled between the outputs of the first push-pull amplifier and the second push-pull amplifier.

[0112] Clause 67. The method according to any one of Clauses 53 to 66, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the H-bridge circuit is embodied by a gate driver circuit including a non-inverting gate driver including the first push-pull amplifier and an inverting gate driver including the second push-pull amplifier.

[0113] Clause 68. The method according to Clause 67, wherein the gate driver circuit outputs the bipolar square wave signal as a differential signal pair, which is output by the respective non-inverting gate driver and the inverting gate driver.

[0114] Clause 69. The method according to one of Clauses 53 to 68, wherein the distortion is compensated using a resistor-capacitor circuit (RC circuit).

[0115] Experts in the field relating to the disclosure will be able to think of many modifications and other implementations of the disclosure set forth herein that incorporate the advantages of the teachings set forth in the foregoing description and the accompanying figures. It is therefore understood that the disclosure is not intended to be limited to the specific implementations disclosed and that modifications and other implementations are intended to fall within the scope of protection of the accompanying claims. Although the foregoing description and the accompanying figures describe exemplary implementations in the context of certain exemplary combinations of elements and / or functions, it is further understood that alternative implementations can provide other combinations of elements and / or functions without deviating from the scope of protection of the accompanying claims.In this respect, other combinations of elements and / or functions than those explicitly described above are conceivable, as can be demonstrated in some of the accompanying claims. Although specific terms are used herein, they are used only in a general and descriptive sense and not for the purpose of limitation.

Claims

[1] Position sensor, comprising: a transformer-based measuring device that can be connected to a moving object, wherein the transformer-based measuring device includes an excitation coil and a plurality of sensing coils; and an excitation circuit for converting a unipolar square wave signal into a bipolar square wave signal to drive the excitation coil to generate an alternating magnetic field and induce output signals in the plurality of detection coils that vary according to the position of the object, wherein the excitation circuit includes: an H-bridge circuit including push-pull amplifiers arranged in two branches, wherein the H-bridge circuit is intended to convert the unipolar square wave signal into the bipolar square wave signal; and a compensation circuit coupled between the two branches of the H-bridge circuit, wherein the compensation circuit serves to to compensate for any distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge circuit. [2] Position sensor according to claim 1, wherein the position sensor comprises a processing circuit to process the output signals in order to determine the position of the object. [3] Position sensor according to claim 1, wherein the unipolar square wave signal is a first unipolar square wave signal and the excitation circuit includes a polarity inverter to convert the first unipolar square wave signal into a second unipolar square wave signal which is opposite in polarity to the first unipolar square wave signal, and wherein the push-pull amplifiers include a first push-pull amplifier driven by the first unipolar square wave signal and a second push-pull amplifier driven by the second unipolar square wave signal. [4] Position sensor according to claim 3, wherein each of the first push-pull amplifier and the second push-pull amplifier includes a complementary pair of transistors connected in a push-pull configuration. [5] Position sensor according to claim 4, wherein the gates of the complementary transistor pair of the first push-pull amplifier are driven by the first unipolar square wave signal and the gates of the complementary transistor pair of the second push-pull amplifier are driven by the second unipolar square wave signal. [6] Position sensor according to claim 4, wherein the complementary transistor pair includes a high-side transistor for coupling the excitation coil to a first supply rail and a low-side transistor for coupling the excitation coil to a second supply rail. [7] Position sensor according to claim 3, wherein the H-bridge circuit is embodied by a gate driver circuit including a non-inverting gate driver that includes the first push-pull amplifier and an inverting gate driver that includes the second push-pull amplifier. [8] Position sensor according to claim 7, wherein the gate driver circuit is to output the bipolar square wave signal as a differential signal pair, which is output by the respective non-inverting gate driver and the inverting gate driver. [9] Position sensor according to claim 1, wherein the compensation circuit is a resistor-capacitor circuit (RC circuit). [10] Excitation circuit, comprising: an H-bridge circuit for converting a unipolar square wave signal into a bipolar square wave signal for driving an excitation coil of a transformer-based measuring device, wherein the H-bridge circuit includes push-pull amplifiers arranged in two branches; and a compensation circuit coupled between the two branches of the H-bridge circuit, wherein the compensation circuit serves to to compensate for any distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge circuit. [11] Excitation circuit according to claim 10, wherein the bipolar square wave signal includes pulses whose amplitude alternates between a first supply rail and a second supply rail. [12] Excitation circuit according to claim 10, wherein each of the push-pull amplifiers includes a complementary pair of transistors connected in a push-pull configuration. [13] Excitation circuit according to claim 10, wherein the unipolar square wave signal is a first unipolar square wave signal and the excitation circuit includes a polarity inverter to convert the first unipolar square wave signal into a second unipolar square wave signal which is opposite in polarity to the first unipolar square wave signal, and wherein the push-pull amplifiers include a first push-pull amplifier driven by the first unipolar square wave signal and a second push-pull amplifier driven by the second unipolar square wave signal. [14] Excitation circuit according to claim 13, wherein each of the first push-pull amplifier and the second push-pull amplifier includes a complementary pair of transistors connected in a push-pull configuration. [15] Excitation circuit according to claim 14, wherein gates of the complementary transistor pair of the first push-pull amplifier are driven by the first unipolar square wave signal and the gates of the complementary transistor pair of the second push-pull amplifier are driven by the second unipolar square wave signal. [16] Excitation circuit according to claim 14, wherein the complementary transistor pair includes a high-side transistor for coupling the excitation coil to a first supply rail and a low-side transistor for coupling the excitation coil to a second supply rail. [17] Excitation circuit according to claim 10, wherein the H-bridge circuit is to output the bipolar square wave signal as a differential signal pair for input at the respective ends of the excitation coil. [18] Excitation circuit according to claim 17, wherein the push-pull amplifiers output each of the differential signal pair. [19] Excitation circuit according to claim 10, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the compensation circuit includes a first compensation circuit coupled to an output of the first push-pull amplifier and a second compensation circuit coupled to the output of the second push-pull amplifier. [20] Excitation circuit according to claim 10, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the compensation circuit is coupled between the outputs of the first push-pull amplifier and the second push-pull amplifier. [21] Excitation circuit according to claim 10, wherein the excitation circuit comprises a voltage buffer to transfer the bipolar square wave signal from the H-bridge circuit to the compensation circuit. [22] Excitation circuit according to claim 10, wherein the push-pull amplifiers include a first push-pull amplifier and a second push-pull amplifier, and wherein the H-bridge circuit is embodied by a gate driver circuit including a non-inverting gate driver including the first push-pull amplifier and an inverting gate driver including the second push-pull amplifier. [23] Excitation circuit according to claim 22, wherein the gate driver circuit is to output the bipolar square wave signal as a differential signal pair, which is output by the respective non-inverting gate driver and the inverting gate driver. [24] Excitation circuit according to claim 10, wherein the compensation circuit is a resistor-capacitor circuit (RC circuit). [25] Procedures, comprehensive: Converting a unipolar square wave signal into a bipolar square wave signal to drive an excitation coil, including the conversion of the unipolar square wave signal: Applying the unipolar square wave signal to an H-bridge circuit with push-pull amplifiers arranged in two branches, wherein the H-bridge circuit converts the unipolar square wave signal into the bipolar square wave signal; and Compensating for the distortion in the bipolar square wave signal caused by the excitation coil acting as an inductive load on the H-bridge circuit. [26] Method according to claim 25, wherein the excitation coil belongs to a transformer-based measuring device connected to a moving object and including a plurality of sensing coils, wherein the bipolar square wave signal drives the excitation coil to generate an alternating magnetic field and to induce output signals in the plurality of sensing coils which vary according to a position of the object, and wherein the method includes processing the output signals to determine the position of the object.

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