Electric motor controller and related methods

Abstract

To provide an electric motor controller and related methods.SOLUTION: A method of controlling an electric motor comprises: calculating, by a motor controller, setpoint Q-D signals based on a setpoint speed signal, the setpoint Q-D signals representing a setpoint position of a magnetic field relative to a rotor of the electric motor; serially sending, by the motor controller, the setpoint Q-D signals to a field-oriented controller disposed within a package distinct from the motor controller; converting, by the field-oriented controller, the setpoint Q-D signals to setpoint α-β signals that represent setpoint position of the magnetic field relative to a stator of the electric motor; transforming, by the field-oriented controller, the setpoint α-β signals into setpoint voltage signals; and gating, by the field-oriented controller, an inverter based on the setpoint voltage signals.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 556,246, entitled "Sensored Field Oriented Control Signal Processing," filed February 21, 2024, which is incorporated herein by reference as if reproduced in full below. [Background technology]

[0002] Speed ​​control of electric motors plays an increasingly important role in a variety of industrial and consumer applications, ranging from household appliances to complex manufacturing systems. The advent of electronic control systems has led to a major shift toward more sophisticated methods that utilize microcontrollers, sensors, and advanced algorithms to achieve precise and efficient speed regulation. Electronic systems not only improve performance and reliability, but also increase flexibility with regard to speed regulation and energy efficiency. Summary of the Invention

[0003] One example is a method of controlling an electric motor, the method including: calculating, by a motor controller, a setpoint QD signal based on a setpoint speed signal, the setpoint QD signal representing a setpoint position of a magnetic field relative to a rotor of the electric motor; serially transmitting, by the motor controller, the setpoint QD signal to a field-oriented controller disposed in a package separate from the motor controller; converting, by the field-oriented controller, the setpoint QD signal to a setpoint α-β signal representing a setpoint position of the magnetic field relative to a stator of the electric motor; converting, by the field-oriented controller, the setpoint α-β signal to a setpoint voltage signal; and gating, by the field-oriented controller, an inverter based on the setpoint voltage signal.

[0004] In an exemplary method, serially communicating the setpoint QD signal may include transmitting at 1 megabit / second or less.

[0005] The exemplary method may further include serially receiving, by the motor controller, a measurement speed signal and a measurement QD signal, where the measurement QD signal represents a position of a magnetic field relative to a rotor of the electric motor, and calculating a setpoint QD signal further includes calculating based on the setpoint speed signal, the measurement speed signal, and the measurement QD signal. Serially transmitting the setpoint QD signal may include transmitting at 1 megabit / second or less, and serially receiving the measurement speed signal and the measurement QD signal may include receiving at 1 megabit / second or less. Serially receiving may include receiving the setpoint speed signal, the measurement speed signal, and the measurement QD signal via serial communication at 1 megabit / second or less.

[0006] The exemplary method may further include receiving, by a field-oriented controller, current signals from current sensors associated with the electric motor, converting the current signals into measured α-β signals representing a position of a magnetic field relative to a stator of the electric motor, receiving a position indication from a position sensor coupled to the electric motor and generating a position signal and a measured speed signal from the position indication, converting the measured α-β signals and the position signal into measured QD signals representing a measured position of the magnetic field relative to a rotor of the electric motor, and serially transmitting the measured QD signals and the measured speed signal to a motor controller. Calculating the setpoint QD signal may further include calculating based on the setpoint speed signal, the measured speed signal, and the measured QD signal. The exemplary method may further include converting the measured α-β signals and the position signal into the measured QD signal synchronously with the position signal. The exemplary method may further include measuring, by the field-oriented controller, a temperature of the semiconductor substrate to generate a measured temperature, and delaying propagation of the measured α-β signals based on the measured temperature to compensate for processing delays in generating the position signal.

[0007] Another example is a packaged semiconductor product comprising: a position sensing terminal, a current sensing terminal, a serial bus terminal, and a gate terminal; a position sensor interface coupled to the position sensing terminal, the position sensor interface configured to generate a position signal and a speed signal; a current sensor interface coupled to the current sensing terminal, the current sensor interface configured to generate a current sense signal; and a reference frame converter coupled to the current sense signal and the position signal, the reference frame converter configured to convert a polyphase current reference frame of an electric motor into a measured QD signal indicative of a position of a magnetic field relative to a rotor of the electric motor. a reference frame converter; a communication interface coupled to the serial bus terminals, the speed signal, and the measurement QD signal, the communication interface configured to serially transmit the speed signal and the measurement QD signal to the motor controller via the serial bus terminals, and the communication interface may be further configured to receive a setpoint QD signal via the serial bus terminals; an inverse reference frame converter coupled to the setpoint QD signal, the inverse reference frame converter configured to convert the setpoint QD signal into setpoint signals for a plurality of phases of the electric motor; and a PWM generator coupled to the setpoint signal and configured to drive gate signals to the gate terminals.

[0008] In an exemplary packaged semiconductor product, the communication interface may be configured to serially transmit the speed signal and the measurement QD signal at 1 megabit / second or less.

[0009] In an exemplary packaged semiconductor product, the communication interface may be configured to serially receive the setpoint QD signal at 1 megabit / second or less.

[0010] In an exemplary packaged semiconductor product, the reference frame converter may include a Clarke converter coupled to the current sense signal and configured to generate a measurement α-β signal representative of a magnetic field position relative to a stator of the electric motor, and a Park converter coupled to the position signal and the measurement α-β signal, the Park converter configured to generate a measurement QD signal. The inverse reference frame converter may include an inverse Park converter coupled to the setpoint QD signal, the inverse Park converter configured to generate a setpoint α-β signal representative of a setpoint position of the electric field relative to the stator, and an inverse Clarke converter coupled to the setpoint α-β signal and configured to generate the setpoint signal. The exemplary packaged semiconductor product may further include delay logic communicatively disposed between the Clarke converter and the Park converter, the delay logic configured to compensate for a computational delay of the position sensor interface. The exemplary packaged semiconductor product may further include a temperature sensor disposed within the packaged semiconductor product and controllable delay logic coupled to the temperature sensor and communicatively disposed between the Clark converter and the Park converter, the controllable delay logic configured to compensate for both a static computation delay and a temperature-dependent computation delay of the position sensor interface. The exemplary packaged semiconductor product may further include controllable delay logic communicatively disposed between the Clark converter and the Park converter, the controllable delay logic configured to detect a clock frequency and compensate for the frequency-dependent computation delay of the position sensor interface. The exemplary packaged semiconductor product may further include a temperature sensor disposed within the packaged semiconductor product and controllable delay logic coupled to the temperature sensor. The controllable delay logic communicatively disposed between the Clark converter and the Park converter, the controllable delay logic may be configured to compensate for a static computation delay of the position sensor interface and to compensate for a temperature-dependent computation delay of the position sensor interface.

[0011] In an exemplary packaged semiconductor product, the current sensor interface may be configured to receive an analog signal from the current sense terminal and generate a current sense signal in digital form.

[0012] In an exemplary packaged semiconductor product, the position sensor interface may be configured to receive an analog signal from the position detection terminal and generate a position signal in digital form.

[0013] An exemplary packaged semiconductor product may include a semiconductor substrate, with the position sensor interface, current sensor, reference frame converter, communication interface, inverse reference frame converter, and PWM generator all implemented on the semiconductor substrate. [Brief explanation of the drawings]

[0014] Exemplary embodiments will now be described in detail with reference to the accompanying drawings. [Figure 1] FIG. 1 illustrates a block diagram of an exemplary motor control system. [Figure 2] A functional block diagram of a motor control system is shown. [Figure 3] 1 shows a block diagram of an exemplary reference frame converter. [Figure 4] 1 shows a block diagram of an exemplary reference frame converter implementing a controllable delay. [Figure 5] FIG. 1 illustrates a block diagram of an exemplary motor control system. [Figure 6A] 1 illustrates a method according to at least some embodiments. [Figure 6B] 1 illustrates a method according to at least some embodiments.

[0015] definition Various terms are used to refer to particular system components. Different companies may refer to a component by different names, and this specification does not intend to distinguish between components that differ in name but not function. In the following description and claims, the terms "including" and "comprising" are used in an open-ended manner and, therefore, should be interpreted to mean "including, but not limited to." Also, the term "couple" or "couples" is intended to mean either an indirect connection or a direct connection. Thus, when a first device couples to a second device, the connection may be by a direct connection or by an indirect connection via other devices and connections.

[0016] As used herein, "a," "an," and "the" refer to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a processor" programmed to perform various functions refers to one processor programmed to perform each and every function, or to more than one processor collectively programmed to perform each of the various functions. For clarity, an initial reference to "a referent" and then a subsequent reference to "the referent" for purposes of the preceding description does not preclude the referenced referent from being plural.

[0017] The terms "input" and "output," when used as nouns, refer to connections and should not be read as verbs requiring an action. For example, a position sensor circuit may define a position output. The position output may be a multi-bit digital word that represents the position of a rotor in an electric motor. In systems implemented directly in hardware (e.g., on a semiconductor substrate), these "inputs" and "outputs" define electrical connections.

[0018] "Signal" or "signals" shall mean any form of transmitted or received data that conveys information. Thus, "signal" encompasses both analog signals, which are continuous waveforms that vary over time, and multi-bit digital words, which are discrete, quantized representations of data made up of multiple binary digits (bits) that encode information in a structured format. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following description relates to various embodiments of the present invention. While one or more of these embodiments may be preferred, the disclosed embodiments should not be construed or otherwise used as limiting the scope of the present disclosure, including the claims. In addition, those skilled in the art will understand that the following description has broad applicability, and the description of any embodiment is intended to be merely an example of that embodiment and is not intended to imply that the scope of the present disclosure, including the claims, is limited to that embodiment.

[0020] Various examples relate to electric motor controllers and related methods. More specifically, various examples relate to field-oriented controllers as packaged semiconductor products. The field-oriented controller implements "fast" aspects of motor control, such as Clarke and Park transforms, and leaves to other external devices the implementation of user-programmable and / or "slow" aspects of motor control, such as proportional-integral-differential (PID) control loops. In this manner, the field-oriented controller can be used in multiple different front-end control configurations, with different control parameter implementations (e.g., speed, position, torque), and with various electric motor types, such as brushless DC and three-phase AC motors (e.g., induction motors and synchronous motors). This specification then discusses exemplary implementations.

[0021] 1 illustrates, in block diagram form, an example motor control system 100. Specifically, the example motor control system 100 includes a motor controller 102, a field-oriented controller 104, a three-phase inverter 106, an electric motor 108, and a position sensor 110. The example motor controller 102 defines a setpoint input 112 and a serial bus connection 114. The example motor controller 102 receives a setpoint signal via the setpoint input 112 and a measurement signal via the serial bus connection 114. The motor controller 102 performs various user-specific calculations, such as a user-specific proportional-integral-derivative control loop, and communicates control values ​​to the field-oriented controller 104 via the serial bus connection 114. The various communicated control values ​​will be described in more detail below after the introduction of a reference frame converter in the field-oriented controller 104. The serial bus protocol, and therefore the exact electrical configuration of the serial bus, may implement any suitable bidirectional serial bus communication scheme, such as the Inter-Integrated Circuit (I2C) protocol or the Serial Peripheral Interface (SPI) protocol. The motor controller 102 may control based on any controllable parameter of the motor, such as speed, motor position, or torque, and combinations. Thus, the setpoint input may be a speed setpoint, a position setpoint, or a torque setpoint. Similarly, the measurement signal may be speed, motor position, or torque. Various embodiments were developed in the context of a system for controlling motor speed, and the following specification is based on that development context. However, the development context of speed control should not be read as limiting the applicability of the various examples.

[0022] The exemplary field-oriented controller 104 is a packaged semiconductor product with various pins or terminals electrically accessible outside the package. The exemplary field-oriented controller 104 defines a serial bus terminal 116, a set (e.g., six) of gate terminals 118, a set (e.g., three) of current sense terminals 120, and a set (e.g., five) of position sense terminals 122. Additional terminals, such as power and ground terminals, may be present but are not shown to avoid overly complicating the discussion. While only one serial bus terminal 116 is shown, there may be more than one depending on the serial communication protocol implemented between the motor controller 102 and the field-oriented controller 104. Similarly, while only one position sense terminal is shown for the set of position sense terminals 122, more than one position sense terminal may be implemented to accommodate multiple types of position sensors 110.

[0023] The set of gate terminals 118 is coupled to the three-phase inverter 106. Specifically, the three-phase inverter 106 receives gate signals from the field-oriented controller 104, which the three-phase inverter 106 uses to provide voltage and current to the electric motor 108 via motor leads 124. In other words, the three-phase inverter 106 receives on / off signals to turn on or off high-side and low-side electrically controlled switches, such as field-effect transistors (FETs). Thus, the gate signals provided by the field-oriented controller 104 control the conductive states of the FETs to provide three-phase voltage and current to the electric motor 108. While the example motor control system 100 of FIG. 1 shows the field-oriented controller 104 directly coupled to the three-phase inverter 106, in other cases, one or more gate driver circuits may exist between the field-oriented controller 104 and the three-phase inverter 106. That is, although the field oriented controller 104 may provide a Boolean gate signal, the field oriented controller 104 may not be designed and constructed to drive sufficient voltage and current to control the gates of the power semiconductor FETs in the three-phase inverter 106. The gate driver circuitry may be selected based on the voltage and current requirements of the electrically controlled switches.

[0024] With continued reference to FIG. 1 , the exemplary motor control system 100 includes an electric motor 108 and an attached position sensor 110. The electric motor 108 can be of any suitable form, such as an AC synchronous motor, an AC induction motor, or a brushless DC motor (driven similarly to its AC counterpart). Various embodiments have been developed in the context of an electric motor 108 that is a brushless DC motor, and the following description is based on that context. However, those skilled in the art, with the benefit of this disclosure, can apply the teachings of the field-oriented controller 104 to many different types of electric motors. Although not specifically shown in FIG. 1 , the electric motor 108 has a rotating portion, or rotor, and a stationary portion, or stator. Voltage and current applied to the stator via motor leads 124 generate a rotating magnetic field. The rotor's magnetic field is attracted to the stator's rotating field, causing the rotor to rotate.

[0025] The position sensor 110 measures or detects the physical position of the rotor. Any suitable position sensor 110 technology can be used, such as a Hall effect sensor, an optical or magnetic encoder, or a resolver using a rotary transformer. In any case, data related to the instantaneous rotational position of the rotor is provided to the field-oriented controller 104 via a set of position detection terminals 122.

[0026] Continuing to refer to FIG. 1 , and now particularly to the internal components of field-oriented controller 104. In an exemplary case, the functionality of field-oriented controller 104 is implemented on a single semiconductor die or semiconductor substrate 126. That is, during semiconductor processing, many such field-oriented controllers may be built simultaneously on a semiconductor wafer. After fabrication is complete, the various devices are cut or singulated. Each singulated die is then packaged as a semiconductor product, with the various electrical connections (e.g., bond pads) on the die electrically coupled to externally accessible terminals.

[0027] Starting at the bottom right, the example field-oriented controller 104 includes a position sensor interface 128 coupled to the set of position detection terminals 122. The position sensor interface 128 defines a speed output 130 and a position output 132. The position sensor interface 128 is designed and constructed to generate a speed signal that is driven to the speed output 130 and a position signal that is driven to the position output 132. In some implementations, the rotor of the electric motor 108 may rotate at 10,000 revolutions per minute (RPM) or more. To ensure that other components of the field-oriented controller 104 properly utilize the position signal, the position sensor interface 128 can sample and drive an updated position signal at or above the Nyquist rate, taking into account the rotor's speed. In one example implementation, the position sensor interface 128 samples the position at a frequency of approximately 1 megahertz, with each sample generating a 20-bit multi-bit word representing the position.

[0028] The example field-oriented controller 104 further defines a current sensor interface 134 coupled to the set of current sense terminals 120, the current sensor interface defining a set of current sense outputs 136. The current sensor interface 134 is designed and constructed to read indications of phase currents on the motor leads 124 and generate a set of current sense signals, one signal for each motor lead 124. In the example of FIG. 1 , the individual phase currents in the motor leads 124 are sampled by current transformers, such as current transformer 138. However, any suitable current sensing technique, such as Hall-effect sensing and current-sensing resistors, may be used. To enable other components of the field-oriented controller 104 to properly utilize the set of current sense signals, the current sensor interface 134 may sample and drive updated position signals at or faster than the Nyquist rate relative to the frequency of the signal applied to the electric motor 108. In one exemplary implementation, the current sensor interface 134 samples the phase current at 100,000 samples per second, with each sample producing a 16-bit multi-bit word representing the instantaneous current.

[0029] Continuing with reference to FIG. 1 , the example field-oriented controller 104 further includes a reference frame converter 140. The reference frame converter 140 defines a set of current sense inputs 142 coupled to the set of current sense outputs 136, a position input 144 coupled to the position output 132, and a QD output 146. The reference frame converter 140 receives the position signals from the position sensor interface 128 and the current sense signals from the current sensor interface 134. The reference frame converter 140 is designed and constructed to convert the multi-phase current reference frame of the electric motor 108 into measured QD signals representing the position of the stator's magnetic field relative to the electric motor's rotor. The reference frame converter 140 is described in more detail below with reference to FIG. 2 .

[0030] The exemplary field-oriented controller 104 further includes a communication interface 148 (labeled "Serial Interface" in the figures) coupled to the serial bus terminal 116, the QD output 146, the velocity output 130, and the position output 132. Thus, the communication interface 148 receives the velocity and / or position signals from the position sensor interface 128 and the measured QD signal from the reference frame converter 140. The communication interface 148 is designed and constructed to serially transmit the velocity and / or position signals, along with the measured QD signal, to the motor controller 102 via the serial bus terminal 116. The communication interface 148 is further configured to receive a setpoint QD signal from the motor controller 102 via the serial bus terminal 116. In an exemplary manner, serially communicating the setpoint QD signal may include transmitting at 1 megabit per second or less.

[0031] The exemplary communications interface 148 communicates at a relatively slow speed compared to the “high-speed” calculations within the field-oriented controller 104. For example, the communications interface 148 can transmit data such as measured velocity signals, measured position signals, and measured QD signals at 1 megabit / second or less. Similarly, the communications interface 148 can receive data such as setpoint QD signals from the motor controller 102 at 1 megabit / second or less. Assuming that the position sensor interface 128 samples position at a frequency of approximately 1 megahertz, with each sample generating a 20-bit multi-bit word representing position, not all of the position signals can be communicated via the communications interface 148.

[0032] The exemplary field-oriented controller 104 further includes an inverse reference frame converter 150. The inverse reference frame converter 150 defines a set of setpoint QD inputs 152 coupled to the communication interface 148, a position input 154 (indicated by a bubble "A") coupled to the position output 132, and a setpoint voltage output 156. The inverse reference frame converter 150 receives the setpoint QD signals from the motor controller 102 (via the communication interface 148) and the position signals from the position sensor interface 128. The inverse reference frame converter 150 is designed and constructed to convert the setpoint QD signals into setpoint voltage signals for multiple phases of the electric motor 108. The inverse reference frame converter 150 is described in more detail below with reference to FIG. 2.

[0033] 1 , the example field-oriented controller 104 further includes a pulse width modulation generator (hereinafter simply PWM generator 158). The PWM generator 158 defines a set of set point voltage inputs 160, and the PWM generator 158 is coupled to the set of gate terminals 118. The PWM generator 158 is designed and constructed to drive gate signals onto the set of gate terminals 118, which in turn causes the three-phase inverter 106 to drive current into the electric motor 108.

[0034] The field-oriented controller 104 further includes a clock circuit 162. The clock circuit 162 is shown unconnected. However, the clock circuit 162 may be connected to all of the various functional blocks of the field-oriented controller 104, but these connections are not shown to avoid overcomplicating the diagram. The clock signal provided by the clock circuit 162 may have a frequency of 30 MHz or more and 60 MHz or less. The functions of the reference frame converter 140 and the inverse reference frame converter 150 are implemented digitally as a hardware-based system or hardware logic. That is, calculations are performed based on digital words, such as with combinational logic and / or sequential logic. With the exception of the analog aspects of the position sensor interface 128 and the current sensor interface 134, these functions are also implemented as hardware logic. Thus, the field-oriented controller 104 may be an application-specific integrated circuit that does not include a processor or microprocessor that executes software.

[0035] FIG. 2 shows a functional block diagram of motor control system 100. Specifically, FIG. 2 shows motor controller 102 and field-oriented controller 104 in more detail. Referring first to motor controller 102, the example motor controller 102 includes a processor 200, a Q-error block 202, a Q-controller 204, a D-error block 206, and a D-controller 208. Processor 200 is communicatively coupled to setpoint input 112. Processor 200 may be communicatively coupled to a velocity signal from position sensor interface 128 and / or a position signal from position sensor interface 128. In this illustration, processor 200 may perform user-specific calculations in generating calculated Q-D signals, labeled Qcalc and Dcalc, respectively. Each set of Qcalc and Dcalc signals is a digital word. However, Qcalc and Dcalc represent setpoint voltage values. Although processor 200 is shown directly coupled to position sensor interface 128, in practice velocity and / or position signals are provided to processor 200 via communications interface 148 (FIG. 1), which is not shown in FIG. 2 to avoid further complicating the illustration.

[0036] Q error block 202 is coupled to the Qcalc signal from processor 200 and to a measured Q signal (labeled Qmeasured in the figure) from field-oriented controller 104. Q error block 202 is designed and constructed to calculate a Q error signal that is applied to Q controller 204. Q controller 204 may then implement any suitable closed-loop control, such as a PID controller, which is designed and constructed to generate a setpoint Q value, labeled Qsp in the figure. Although the Qmeasured signal is shown coupled directly to Q error block 202 and the Qsp signal is shown coupled directly to field-oriented controller 104, in reality the signals are provided via communication interface 148 (FIG. 1). However, the communication interface is not shown in FIG. 2 to avoid further complicating the figure.

[0037] Similarly, D error block 206 is coupled to the D calc signal from processor 200 and to a measured D signal (labeled D measured in the figure) from field-oriented controller 104. D error block 206 is designed and constructed to calculate a D error signal that is applied to D controller 208. D controller 208 may then implement any suitable closed-loop control, such as a PID controller, which is designed and constructed to generate a setpoint Q value, labeled D sp in the figure. Although the D measured signal is shown coupled directly to D error block 206 and the D sp signal is shown coupled directly to field-oriented controller 104, in reality the signals would be provided via communication interface 148 ( FIG. 1 ).

[0038] 2, the field-oriented controller 104 will now be considered. The field-oriented controller 104 comprises a position sensor interface 128, a current sensor interface 134, a reference frame converter 140, an inverse reference frame converter 150, and a PWM generator 158. An exemplary reference frame converter 140 comprises a Clark converter 210 and a Park converter 212. The Clark converter 210 is coupled to the current sense signal from the current sensor interface 134. The Clark converter 210 is designed and constructed to generate a measured α-β signal representative of the position of the stator's magnetic field relative to the stator 108. In other words, the Clark converter 210 converts the phase current i a , i b , and i c The stator current coordinate system is designed and constructed to convert the multiphase current coordinate system of the stator into a measured α-β signal with a stationary reference to the stator.

[0039] In the example of FIG. 2 , the Park converter 212 is coupled to the position signal from the position sensor interface 128 and the measured α-β signal from the Clark converter 210. The exemplary Park converter 212 is designed and constructed to generate a measured QD signal based on the position signal and the measured α-β signal. In other words, the Park converter 212 is designed and constructed to convert the measured α-β signal, which is expressed in terms of a stationary reference to the stator, into a measured QD signal that represents the position of the stator's magnetic field relative to the rotor's magnetic field. Each Qmeasured signal can be considered an indication of the amount of instantaneous torque provided by the electric motor 108, where Qmeasured is sometimes referred to as a "quadrature current." The Dmeasured signal can be considered an indication of the amount of instantaneous magnetizing current, where Dmeasured is sometimes referred to as a "direct current" or "magnetizing current." For brushless DC motors, the magnetizing current is controlled to be close to zero; however, for other electric motors, such as induction motors, non-zero magnetizing currents can be used.

[0040] Continuing to refer to FIG. 2 , the inverse reference frame converter 150 will now be considered. The exemplary inverse reference frame converter 150 includes an inverse Park converter 214 and an inverse Clarke converter 216. The inverse Park converter 214 is coupled to the position signal from the position sensor interface 128 and the setpoint QD signal from the motor controller 102. The inverse Park converter 214 is designed and constructed to generate a setpoint α-β signal relative to the stator that represents the setpoint position of the voltage applied to the stator. In other words, the inverse Park converter 214 is designed and constructed to convert the setpoint QD signal, expressed in terms of the rotor's rotation, into a setpoint α-β signal that represents the position of the magnetic field relative to the stator.

[0041] An inverse Clarke converter 216 is coupled to the setpoint α-β signal. The inverse Clarke converter 216 is designed and constructed to generate a setpoint voltage signal that is applied to the PWM generator 158. In other words, the inverse Clarke converter 216 is designed and constructed to convert the setpoint α-β signal, expressed in the rotor's stationary reference frame, into a setpoint phase voltage to be applied to the stator.

[0042] In various examples, the functions of Clark converter 210, Park converter 212, inverse Park converter 214, and inverse Clark converter 216 are implemented digitally as a hardware-based system or hardware logic. That is, calculations are performed based on digital words, such as with combinational and / or sequential logic. With the exception of the analog aspects of position sensor interface 128 and current sensor interface 134, these functions are also implemented as hardware logic. Implementing various functions as hardware logic allows for characterization of field-oriented controller 104 and direct hardware compensation for delays and / or processing speed differences between functions. For example, if the instantaneous position signal provided by position sensor interface 128 is time-aligned with the measured α-β signal provided by Clark converter 210, Park converter 212 provides a more accurate measured QD signal. In other words, if the position signal from position sensor interface 128 is synchronized with the corresponding measured α-β signal, a more accurate measured QD signal is generated. However, the position sensor interface 128 may have a longer calculation time (e.g., require more clock cycles) than the combined calculation time of the current sensor interface 134 and the Park converter 210. Some example field-oriented controllers 104 compensate for the difference in calculation time by slowing down or delaying the delivery of the measured α-β signal to the Park converter 212.

[0043] 3 shows a block diagram of an example reference frame converter 300. Specifically, the reference frame converter 300 includes a Clark converter 210 and a Park converter 212, as well as delay logic 302 communicatively disposed between the Clark converter 210 and the Park converter 212. The delay logic 302 receives the measured α-β signals from the Clark converter 210 and implements a propagation delay for each set of values. In other words, the example delay logic 302 imposes a fixed, predetermined delay in communicating the measured α-β signals to the Park converter 212. The delay at least partially compensates for the computational delay of the position sensor interface 128 (FIG. 1). The delay logic 302 may be in any suitable form, such as a shift register-based delay circuit or a fixed set of first-in, first-out buffers.

[0044] The amount of delay implemented by the delay logic 302 can be determined in a number of ways. In one example, during the design phase, the expected computational delay of the position sensor interface 128 can be compared to the expected computational delay of the current sensor interface 134 and Clark converter 210. The delay logic 302 can be designed to provide a predetermined delay based on the difference in the computational delays.

[0045] However, the computational delay of the position sensor interface 128 ( FIG. 1 ) may vary from die to die, even if they are on the same semiconductor wafer. Thus, in other cases, the computational delay may be measured on the semiconductor wafer after construction (e.g., in a “probe” stage), and then a more precise delay may be implemented in the delay logic 302, such as by laser ablation of delay elements, to more precisely control the delay on each die. In other examples, the delay logic 302 may implement a controllable delay based on operating parameters of the field-oriented controller 104. For example, the delay logic 302 may detect a clock frequency via the clock input 304 and compensate for the frequency-dependent computational delay of the position sensor interface 128. In other words, the exemplary delay logic 302 may implement a delay including a “static” computational delay and a frequency-dependent computational delay.

[0046] Returning briefly to FIG. 1 , the example field-oriented controller 104 may include a temperature sensor 170 disposed within the package and, in some cases, on the semiconductor substrate 126. The temperature sensor 170 may be designed and constructed to measure the temperature of the semiconductor substrate 126 and generate a temperature signal that is driven to a temperature output 172. Generating the temperature signal may be done in any suitable manner. In one example, an analog-based measurement (e.g., a resistance temperature measurement) is converted to digital form and driven to the temperature output 172. In other cases, the temperature signal may be calculated digitally, for example, based on the amount of time a signal propagates along a logic chain whose propagation speed is temperature-dependent. The example reference frame converter 140 further includes a temperature input 174. In various examples, the reference frame converter 140 implements a variable delay using the temperature signal.

[0047] 4 shows a block diagram of an example reference frame converter 400 that implements a controllable delay based on temperature. Specifically, the reference frame converter 400 includes a Clark converter 210 and a Park converter 212, as well as delay logic 402 communicatively disposed between the Clark converter 210 and the Park converter 212. The delay logic 402 receives the measured α-β signal from the Clark converter 210 and implements a propagation delay for each set of values. More specifically, the example delay logic 402 receives a temperature signal via the temperature input 174, and the example delay logic 402 implements a controllable delay based on the temperature signal to compensate for the temperature-dependent computational delay of the position sensor interface 128 (FIG. 1). In other words, the example delay logic 402 can compensate for both the “static” computational delay of the position sensor interface 128 and the temperature-dependent computational delay of the position sensor interface 128. In yet another case, the example delay logic 402 may compensate for a static computational delay of the position sensor interface 128 , a temperature-dependent computational delay of the position sensor interface 128 , and a frequency-dependent computational delay of the position sensor interface 128 .

[0048] FIG. 5 illustrates an example motor control system 100 in block diagram form. Specifically, FIG. 5 illustrates the field-oriented controller 104 from FIG. 1 along with a three-phase inverter 106, stator windings 500, and an inductive rotor position sensor 502. The example three-phase inverter 106 includes six FETs. The upper FET has a drain coupled to a DC power supply, and the lower FET has a source coupled to a reference voltage, such as ground. The source of the upper FET and the drain of the lower FET define respective switch nodes coupled to respective leads of the stator windings 500. More specifically, the example stator 500 is a three-phase stator connected in a "Y" configuration, thus defining three stator leads. Each stator lead is associated with a set of FETs, including an upper FET and a lower FET, within the three-phase inverter 106. Thus, the field-oriented controller 104 gates (eg, PWMs) the three-phase inverter 106, thereby providing voltage and current to the stator windings 500 to generate a rotating magnetic field relative to the stator windings.

[0049] 5, the current sensors used to sense the phase currents are current sensing resistors 504, each associated with a motor lead. Accordingly, the example current sensor interface 134 is designed and constructed to sense the voltage across each of the current sensing resistors and convert the sensed voltage into the sensed current signal described above. Again, the field effect controller 104 can interface with other different types of current sensors, such as Hall effect sensors.

[0050] Finally, the example field oriented controller 104, and specifically the position sensor interface 128, is shown coupled to a position sensor in the form of an inductive rotor position sensor 502. Thus, in this example, the field oriented controller implements five terminals coupled to the position sensor interface 128. Specifically, the example position sensor interface 128 can detect rotor position based on analog signals from the inductive rotor position sensor 502 and generate position and speed signals based thereon.

[0051] 6A and 6B illustrate a method according to at least some embodiments. Specifically, the method begins (block 600) and includes steps implemented within a motor controller, as indicated by dashed box 602. The exemplary motor controller serially receives a measurement signal and a measurement QD signal, where the measurement QD signal represents the position of a magnetic field relative to a rotor of an electric motor (block 604). The measurement signal may be a measurement speed signal, a measurement position signal, or both. The motor controller calculates a setpoint QD signal based on the setpoint speed or position signal, where the setpoint QD signal represents the setpoint position of a stator magnetic field relative to the rotor of the electric motor (block 606). The motor controller can then serially transmit the setpoint QD signal to a field-oriented controller disposed in a package separate from the motor controller (block 608).

[0052] Consider now the method steps associated with the field-oriented controller, as shown within dashed box 610 in FIG. 6B. The method may further include the field-oriented controller converting the setpoint QD signal into a setpoint α-β signal representing a setpoint position of the stator's magnetic field relative to the stator (block 612). The field-oriented controller may then convert the setpoint α-β signal into a setpoint signal (block 614). The field-oriented controller then gates the inverter based on the setpoint current signal (block 616). The field-oriented controller receives a current signal from a current sensor associated with the electric motor (block 618). The field-oriented controller receives a position indication from a position sensor coupled to the electric motor and generates a position signal and a measured speed signal from the position indication (block 620). The field-oriented controller may then convert the current signal from the current sensor into a measured QD signal (block 622) and serially transmit the measured QD signal to the motor controller (block 624). The method then ends (block 626) and is repeated continuously during operation of the electric motor.

[0053] Thus, the exemplary field-oriented controller 104 implements "fast" aspects of motor control, such as Clarke and Park transformations, and leaves to other external devices the implementation of user-programmable and / or "slow" aspects of motor control, such as proportional-integral-derivative (PID) control loops. In this manner, the field-oriented controller can be used in multiple different front-end control configurations and with a variety of electric motor types, such as brushless DC and three-phase AC motors (e.g., induction motors and synchronous motors).

[0054] Although many of the electrical connections in the drawings are shown as direct couplings with no intervening devices, and are not explicitly stated as such in the description above, this paragraph nevertheless serves as the basis for precedent in the claims to refer to any electrical connection as a "direct coupling" with respect to the electrical connection shown in the drawings with no intervening devices.

[0055] The foregoing is intended as an exemplification of the principles and various embodiments of this invention. Numerous variations and modifications will be apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.

Claims

1. 1. A packaged semiconductor product comprising: a position detection terminal, a current detection terminal, a serial bus terminal, and a gate terminal; a position sensor interface coupled to the position detection terminal, the position sensor interface configured to generate a position signal and a velocity signal; a current sensor interface coupled to the current sensing terminal, the current sensor interface configured to generate a current sensing signal; a reference frame converter coupled to the current sense signals and the position signals, the reference frame converter configured to convert a polyphase current reference frame of an electric motor into a measurement QD signal representative of a magnetic field position relative to a rotor of the electric motor; a communication interface coupled to the serial bus terminal, the speed signal, and the measurement QD signal, the communication interface configured to serially transmit the speed signal and the measurement QD signal to a motor controller via the serial bus terminal; a communication interface further configured to receive a setpoint QD signal via the serial bus terminal; an inverse reference frame converter coupled to the setpoint QD signal, the inverse reference frame converter configured to convert the setpoint QD signal to setpoint signals for a plurality of phases of the electric motor; a PWM generator coupled to the setpoint signal and configured to drive a gate signal onto the gate terminal.

2. The reference frame converter comprises: a Clarke transducer coupled to the current sense signal and configured to generate a measured α-β signal representative of a magnetic field position relative to a stator of the electric motor; a Park transducer coupled to the position signal and the measured α-β signal, the Park transducer configured to generate the measured QD signal; The inverse reference frame converter comprises: an inverse Park converter coupled to the set point QD signal, the inverse Park converter configured to generate a set point α-β signal representative of a set point position of the electric field relative to the stator; an inverse Clarke transformer coupled to the setpoint α-β signal and configured to generate the setpoint signal.

3. 3. The packaged semiconductor product of claim 2, further comprising delay logic communicatively disposed between the Clark transducer and the Park transducer, the delay logic configured to compensate for a computational delay of the position sensor interface.

4. a temperature sensor disposed within the packaged semiconductor product; 3. The packaged semiconductor product of claim 2, further comprising: controllable delay logic coupled to the temperature sensor and communicatively disposed between the Clark converter and the Park converter, the controllable delay logic configured to compensate for both static and temperature-dependent computational delays of the position sensor interface.

5. 3. The packaged semiconductor product of claim 2, further comprising controllable delay logic communicatively disposed between the Clark converter and the Park converter, the controllable delay logic configured to detect a clock frequency and compensate for a frequency-dependent computation delay of the position sensor interface.

6. a temperature sensor disposed within the packaged semiconductor product; controllable delay logic coupled to the temperature sensor, the controllable delay logic communicatively disposed between the Clark converter and the Park converter, the controllable delay logic comprising: Compensating for static computation delays of the position sensor interface; 3. The packaged semiconductor product of claim 2, further comprising: controllable delay logic configured to compensate for a temperature dependent computational delay of the position sensor interface.

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