Patent Description:
Household and industrial appliances such as ventilation fans, cooling systems, refrigerators, dishwasher, washer/dryer machines, and many other white products/goods typically utilize electric motors that transfer energy from an electrical source to a mechanical load. Electrical energy for driving the electric motors is provided through a drive system, which draws electrical energy from an electrical source (e.g., from an AC low frequency source). The electrical energy is processed through a power converter and converted to a desired form of electrical energy that is supplied to the motor to achieve the desired mechanical output. The desired mechanical output of the motor may be for example the speed of the motor, the torque, or the position of a motor shaft.

Motors and their related circuitries, such as motor drivers, represent a large portion of network loads. The functionality, efficiency, size, and price of motor drivers are challenging and competitive factors that suppliers of these products consider. The function of a power converter in a motor drive includes providing the input electrical signals to the motor, such as voltage, current, frequency, and phase, for a desired mechanical output load motion (e.g., spin/force) on the motor shaft. The power converter in one example may be an inverter transferring a dc input to an ac output of desired voltage, current, frequency, and phase. A controller of the power converter regulates the energy flow in response to signals that are received from a sensor block. The low power sensed signals from the motor or power converter are sent to the controller in a closed loop system by comparing the actual values to the desired values. The controller adjusts the output in comparison of the actual values to the desired values to maintain the target output. Brushless dc (BLDC) motors, which are known for their higher reliability and efficiency, are becoming a popular choice in the market replacing brushed dc and motors. They are widely used in household appliances, such as refrigerators, air conditioners, vacuum cleaners, washers/driers, and other white goods, and power tools such as electric drills, or other electric tools. A BLDC motor requires a power converter, which typically includes an inverter stage as a combination of half-bridge switcher modules. A half-bridge switcher module may include power switches and control blocks inside of an integrated circuit, which provides a compact structure having a smaller size and higher efficiency.

<NPL>) describes a current reconstruction algorithm for three-phase inverters using integrated current sensors in the low-side switches.

Baeurle et al. (https://www. com/sites/default/files/documents/BridgeseSwitch-DirectUseofIPHSignalinFOC. pdf) described direct use of Bridgeswitch™ current sense signal output in field oriented control of brushless DC motors.

<CIT> describes devices and techniques that provide control of a three-phase AC motor.

The invention is defined in device claim <NUM> and method claim <NUM>.

Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

Corresponding reference characters indicate corresponding components throughout the several views of the drawings. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one having ordinary skill in the art that the specific detail need not be employed to practice the present invention. In other instances, well-known materials or methods have not been described in detail in order to avoid obscuring the present invention.

Reference throughout this specification to "one embodiment", "an embodiment", "one example" or "an example" means that a particular feature, structure or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment", "in an embodiment", "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures or characteristics may be combined in any suitable combinations and/or subcombinations in one or more embodiments or examples. Particular features, structures or characteristics may be included in an integrated circuit, an electronic circuit, a combinational logic circuit, or other suitable components that provide the described functionality. In addition, it is appreciated that the figures provided herewith are for explanation purposes to persons ordinarily skilled in the art and that the drawings are not necessarily drawn to scale.

Brushless dc (BLDC) motors are becoming a popular choice for replacing brushed dc and ac motors. They are widely used in household appliances, such as refrigerators, air conditioners, vacuum cleaners, washers/driers, fans, pumps and other white goods, and power tools such as electric drills, or other electric tools. A BLDC motor utilizes a power converter, which typically includes an inverter stage of one or more half-bridge modules. The half-bridge modules generally include power switches, a high-side power switch and a low-side power switch coupled in a half-bridge configuration, and their respective switch controllers to drive the power switches ON or OFF. A motor drive system for a BLDC motor also generally includes a system controller which receives sense signals regarding properties of the motor and sends control signals to the half-bridge modules to control the turn ON and turn OFF of the power switches and therefore control the desired motion of the rotor shaft of the BLDC motor.

A three-phase motor has three terminals, referred to as U, V, and W, with three windings. The windings and subsequent phases are generally referred to by the terminal they correspond with. A motor drive system for the three-phase motor utilizes a system controller and three half-bridge modules to control the magnitude and direction of the three phase currents of the motor: IPHASEU, IPHASEV, IPHASEW. The system controller may employ several different control schemes, such as trapezoidal or sinusoidal commutation. For trapezoidal commutation, current is controlled through motor terminals one pair at a time, with the third motor terminally electrically disconnected. However, since motor terminals are only controlled in pairs, there are only six discreet directions which the motor may be controlled. As such, misalignment is common and control may be choppy at slow motor speeds. Sinusoidal commutation attempts to drive the three motor windings with phase currents, IPHASEU, IPHASEV, IPHASEW, to be sinusoidal in shape. Feedback information of both the motor position and the phase currents along with a quick response to transients is generally necessary for sinusoidal commutation. However, at high motor speeds the transient response of sinusoidal commutation may not be sufficient, and control may significantly degrade at high motor speeds.

Field oriented control is another control scheme that could be utilized by the system controller that takes advantage of representation of the phase currents, IPHASEU, IPHASEV, IPHASEW, as vectors, often referred to as current space vectors. The current space vector for a given winding has the direction representative of the magnetic field produced by that winding and a magnitude proportional to the phase current through the winding. The total stator current may be presented by a vector which is the sum of each current phase vector of each winding of the motor. Each current space vector of the three-phase motor is substantially one hundred twenty degrees (<NUM>°) apart.

For field oriented control (FOC), the current space vectors of phase currents, IPHASEU, IPHASEV, IPHASEW allows for representation of the stator current in a three-axis reference frame of the motor windings, U-axis, V-axis, and W-axis which are one hundred twenty degrees (<NUM>°) apart. The representation of the stator current vector in the three-axis reference frame can be translated to representation of the stator current vector in a two-axis reference frame of the stator, alpha-axis (α-axis) and beta-axis (β-axis) which are ninety degrees (<NUM>°) apart utilizing the Clarke transform. The stator current vector in the two-axis reference frame of the stator can be further represented in the rotating two-axis reference frame of the rotor, direct-axis (d-axis) and quadrature-axis (q-axis) which are ninety degrees (<NUM>°) apart but rotate with respect to the rotor, using the Park transform. The direct d-axis component of the stator current vector produces compression forces which does not turn the rotor while the quadrature q-axis component of the stator current vector produces torque. Proportional-integral (PI) control could then be used to minimize the direct-component and maximize the quadrature-component of the stator current vector. The outputs of the PI control are then converted back to the fixed two-axis reference frame of the stator (α and β axis which are <NUM>° apart) and then to the three-axis reference of the motor windings. As such, a system controller utilizing FOC may have smooth motion at low speeds and efficient operation at high speeds. However, for FOC to be utilized, the system controller should receive the entirety of the phase currents IPHASEU, IPHASEV, IPHASEW. One common technique for a motor drive system to measure the phase currents, IPHASEU, IPHASEV, IPHASEW, is to add shunt resistors in series with the low-side switch of each leg of the half-bridge module. Additional components, such as an operational amplifier and offset components are also added for the system controller to measure the phase currents, IPHASEU, IPHASEV, IPHASEW, which utilizes significant physical space, increases component count, and overall system cost.

In contrast, a BridgeSwitch™ half-bridge module includes a terminal which provides a phase current sense signal (IPH) which is proportional to the current flowing through the low-side switch of a half-bridge module and therefore proportional to a portion of the phase current. However, each of the phase current sense signals provides a portion of their respective sensed phase currents, IPHASEU, IPHASEV, IPHASEW, in particular, the negative portion of the phase currents, IPHASEU, IPHASEV, IPHASEW. As such, at any given point in time, all three phase currents IPHASEU, IPHASEV, IPHASEW may not be available from the phase current sense signals. To utilize FOC, the phase current should be reconstructed from the at least one phase current sense signal (IPH) that is present.

Reconstruction of the phase current has been discussed in a whitepaper titled "<NPL>, However, the reconstruction algorithm proposed in the white paper is a combination of trigonometric calculations and division to produce a reconstruction scaling factor, which can require significant processing power for the system controller. The reconstructed phase current is substantially the product of the reconstruction scaling factor and the phase current sense signal. For example, microcontrollers, such as a <NUM> Cortex-M0 microcontroller, are often used for the system controllers for a motor drive system. These microcontrollers generally have about <NUM>-<NUM> kB flash memory, about <NUM>-<NUM> kB of RAM, with a processing speed of about <NUM>. These microcontrollers may be unable to perform the trigonometric calculations for current reconstruction at a speed fast enough to take advantage of FOC. For example, phase current reconstruction following the proposed process of the white paper may take approximately <NUM> of processing time for the microcontrollers generally used with typical motor drive systems.

For control schemes, such as field oriented control, sensing the phase currents, IPHASEU, IPHASEV, IPHASEW, requires current feedback of the phase currents. At some estimations, a total of twenty-nine components which are external from the half-bridge modules are utilized to provide the current feedback of the three phase currents IPHASEU, IPHASEV, IPHASEW. In contrast, embodiments of the present disclosure utilize a half-bridge module which includes a terminal which provides an internally sensed phase current sense signal (IPH) which is proportional to the current flowing through the low-side switch of a half-bridge module and therefore proportional to a portion of the phase current. As such, a single resistor per half-bridge module may be utilized to provide current feedback of the three phase currents IPHASEU, IPHASEV, IPHASEW, and reduces the external component count for current feedback by ninety percent. For the traditional shunt resistor, the entire phase current flows through the resistor and the power loss due to the shunt resistor may be significant. In contrast, the internally sensed phase current sense signal (IPH) is a much smaller value than the phase current itself. For example, the phase current may be <NUM> ampere (A) while the phase current sense signal may be <NUM>µA. The traditional shunt resistor is typically a <NUM> Ohm resistor while the single resistor is generally <NUM> kOhm to convert the phase current sense signal to a voltage value. The power loss due to the traditional resistor is approximately 220mW while the power loss due to the IPH phase current sense signal is approximately <NUM> mW, a <NUM>% improvement in power loss.

Embodiments of the present disclosure have recognized patterns in the calculation results utilized for phase current reconstruction. In particular, embodiments of the present disclosure have recognized that several repeated patterns occur every sixty degrees (<NUM>°). As such, the three hundred sixty degrees (<NUM>°) of the phase currents can be partitioned into six sectors (Sector <NUM> to Sector <NUM>) of substantially sixty-degree (<NUM>°) increments and the repeated patterns were in response to the stator current angle Θαβ of the stator current vector. As such, the repeated patterns may be represented by a reference table which allows preloading of the calculation results which decreases the processing time for phase current reconstruction. The reference tables may be indexed in response to the stator current angle Θαβ and the selection of the appropriate reference table may be in response to the stator current angle Θαβ and at least one phase current sense signal (IPH). The stator current angle Θαβ may be estimated from the alpha and beta components of the stator current vector. Further, the stored values in the reference table are representative of the reconstruction scaling factor. The reconstructed phase current is substantially the product of the reconstruction scaling factor and the available phase current sense signal. As such, in lieu of performing complicated trigonometric calculations, the system controller utilizes multiple reference tables selected in response to the phase current sense signal (IPH) and the stator current angle Θαβ to reconstruct the phase currents of the motor. Once the phase currents are reconstructed, the system controller may perform a control scheme, such as FOC, to provide the control signals to turn on and turn off various switches of the half-bridge module. As mentioned above, a microcontroller may take as much as <NUM> of processing time to perform the trigonometric calculations of phase current reconstruction, not including the additional amount of processing time to also determine the stator current angle Θαβ. In contrast, a system controller utilizing embodiments of the presented disclosure utilizing reference tables may take approximately <NUM> of processing time to perform phase current reconstruction. As such, embodiments of the present disclosure may reduce the processing time for phase current reconstruction and facilitate field oriented control for motor drive systems.

<FIG> illustrates a multi-phase motor drive system <NUM> including three half-bridge inverter modules 102a, 102b, and 102c, coupled to a high-voltage (HV) bus <NUM> and controlled with a system controller <NUM> to drive a motor <NUM>, such as for example a three-phase motor. As shown, each half-bridge inverter modules 102a, 102b, and 102c and the system controller <NUM> are referenced to return <NUM>. Each half bridge module 102a, 102b, and 102c is coupled to the three phase terminals U, V, and W of the motor <NUM>. The current for each phase/leg of the motor <NUM> is denoted as phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. Further, each half bridge module 102a, 102b, and 102c are configured to output a phase current sense signal IPHU <NUM>, IPHV <NUM>, and IPHW <NUM>, which is representative of their respective phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>, to the system controller <NUM>. In one example, the system controller <NUM> can determine the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> from at least one phase current sense signal IPHU <NUM>, IPHV <NUM>, and IPHW <NUM>, in accordance of the teachings of the present disclosure. It should be appreciated that phase current sense signal IPHU <NUM>, IPHV <NUM>, and IPHW <NUM> may be referred to as first-phase current sense signal IPHU, second-phase current sense signal IPHV, and third-phase current sense signal IPHW while phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> may be referred to as first phase current IPHASEU, second phase current IPHASEV, and third phase current IPHASEW.

Each half-bridge module 102a, 102b, and 102c, includes a high-side power switch 108a, 108b, 108c, and a low-side power switch 110a, 110b, 110c, respectively, coupled together as a power converter or an inverter in a half-bridge configuration. The high-side switches 108a, 108b, 108c, and a low-side switch 110a, 110b, 110c are shown as n-type metal-oxide-semiconductor field-effect transistors with their respective anti-parallel diodes. However, it should be appreciated that other transistor may be used, such as an insulated-gate bipolar transistor (IGBT), bipolar transistors, injection enhancement gate transistors (IEGTs) and gate turn-off thyristors (GTOs). In addition, half-bridge module 102a, 102b, and 102c could be used with power switches which are based on gallium nitride (GaN) semiconductors or silicon carbide (SiC) semiconductors. The half-bridge mid-point terminals HB1, HB2, HB3 between each high-side switch 108a, 108b, 108c and low-side switch 110a, 110b, 110c of their respective half-bridge modules 102a, 102b, and 102c, are coupled to the three phase terminals U, V, W of the multi-phase motor <NUM>. In one example, the motor <NUM> is a brushless three-phase DC motor.

The turn ON and OFF of each high-switch power switch 108a, 108b, 108c, is controlled by its respective high-side switch controller 112a, 112b, 112c while the turn ON and turn OFF of each low-side power switch 110a, 110b, 110c is controlled by its respective low-side switch controller 114a, 114b, 114c. The switching properties of switches 108a, 108b, 108c, 112a, 112b, and 112c are controlled by their respective switch controllers to regulate the energy flow to the motor <NUM>. In other words, the switch controllers 112a, 112b, 112c, 114a, 114b, and114c adjust the outputs to the motor <NUM> to maintain the target operation of the motor <NUM>. In operation, the half-bridge modules 102a, 102b, and 102c provide the input electrical signals (such as voltage, current, frequency, and phase for the desired mechanical output load motion) to the motor <NUM> from the electrical energy supplied by the HV bus <NUM>. In one example, the half-bridge modules 102a, 102b, and 102c control the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> to control the motor <NUM> with to the target operation.

Half-bridge modules 102a, 102b, 102c each include a current sense circuit 115a, 115b, 115c, respectively. As shown, the low-side switch controllers 114a, 114b, 114c, each includes the current sense circuit 115a, 115b, 115c, respectively. The current sense circuit 115a, 115b, 115c are configured to receive the current of their respective low-side power switch 110a, 110b, 110c. In one example, current sense circuit 115a, 115b, 115c receives the drain current of their respective low-side power switch 110a, 110b, 110c. The drain current of the low-side power switches 110a, 110b, 110c are representative of their respective motor phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> when the low-side power switches 110a, 110b, 110c are conducting. In particular, current sense circuit 115a receives the drain current of low-side power switch 110a, which is representative of phase currents IPHASEU <NUM> when low-side power switch 110a is conducting. Current sense circuit 115b receives the drain current of low-side power switch 110b, which is representative of phase currents IPHASEV <NUM> when low-side power switch 110n is conducting. Current sense circuit 115c receives the drain current of low-side power switch 110c, which is representative of phase currents IPHASEW <NUM> when low-side power switch 110c is conducting. As such, current sense circuit 115a, 115b, 115c sense the respective negative values of phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>.

Each current sense circuit 115a, 115b, 115c outputs their respective phase current sense signal IPHU <NUM>, IPHV <NUM>, IPHW <NUM>. In one example, the phase current sense signal IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are current signals. For the example shown, positive phase current is defined as current flowing from the half-bridge module to the motor. As such, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are representative of the negative values of their respective phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. For example, phase current sense signal IPHU <NUM> is representative of the negative values of phase current IPHASEU <NUM>, phase current sense signal IPHV <NUM> is representative of the negative values of phase current IPHASEV <NUM>, and phase current sense signal IPHW <NUM> is representative of the negative values of phase current IPHASEW <NUM>. In one example, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> may be a constant value for positive values of their respective phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. In one example, the constant value is substantially zero. However, in some implementations of the current sense circuits 115a, 115b, and 115c, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> have a minimum non-zero output value even when no current is passing though low-side power switches 110a, 110b, 110c. However, it should be appreciated that the phase current sense signal IPHU <NUM>, IPHV <NUM>, IPHW <NUM> provides positive values for the sensed negative values of phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. As such, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are substantially constant for positive values of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>, respectively, and mirror the negative values of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>, respectively.

The system controller <NUM> is configured to receive one or more command signals from the user input <NUM> to control the operation of motor <NUM>. For example, system controller <NUM> may receive an "ON" command to turn on and begin operation of motor <NUM>, or conversely, may receive an "OFF" command to stop operation of motor <NUM>. Further command signal from user input <NUM> may include the desired mechanical outputs of the motor <NUM>, such as the speed or torque. Further, the system controller <NUM> is also coupled to receive phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> representative of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> of motor <NUM>. The system controller <NUM> utilizes these phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> to control the desired mechanical output of the motor <NUM>.

In response to command signals from the user input <NUM> and the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>, the system controller <NUM> outputs control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> to half-bridge modules 102a, 102b, 102c, respectively, to control the turn ON and turn OFF of high-side power switches 108a, 108b, 108c and low-side power switches 110a, 110b, 110c. In one example, control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> are representative of a command to turn ON or turn OFF the high-side and low-side power switch of the applicable half-bridge module. In another example, control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> may also be representative of switching properties of the respective power switches. Switching properties may include the on-time of the power switch, off-time, the duty ratio (typically the ratio of the on time of the switch to the total switching period), the switching frequency, or the number of pulses per unit time of the power switch. Further, control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> may be voltage signals or current signals.

In one example, control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> are rectangular pulse width waveforms with varying lengths of high and low durations. In one example, a high value for control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> could correspond with turning ON the respective high-side switch 108a, 108b, 108c and turning OFF the respective low-side switch 110a, 110b, 110c. A low value for control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> could correspond with turning ON the respective low-side switch 110a, 110b, 110c and turning OFF the respective high-side switch 108a, 108b, 108c. In response to the respective received control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM>, high-side switch controllers 112a, 112b, 112c drive the turn ON or turn off of high-side switches 110a, 110b, 110c while low-side switch controllers 114a, 114b, 114c drive the turn ON or turn OFF of low-side switches 112a, 112b, 112c.

System controller <NUM> also performs phase current reconstruction in accordance with embodiments of the present disclosure. As discussed above, the received phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are representative of a portion of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> of motor <NUM>. In one example, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are substantially constant for positive values of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>, respectively, and mirror negative values of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>, respectively. Further, the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> are offset by one hundred twenty degrees (<NUM>°) from each other, and the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are also offset by one hundred twenty degrees (<NUM>°) from each other. As such, there are portions of time which one or more of the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are substantially equal to a constant value and do not provide information regarding their respective the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. Some control schemes which may be utilized by the system controller <NUM>, such as field oriented control, utilizes all three phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> to determine the control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM>. As such, in embodiments of the present disclosure, system controller <NUM> includes phase current reconstruction when information regarding one or more of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> is missing due to one or more of the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> substantially equaling a constant value, such as zero or a minimum output of the current sense circuit.

As will be further discussed, the system controller <NUM> reconstructs the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> utilizing the stator current angle Θαβ of the stator current vector and multiple reference tables. The system controller <NUM> further includes a stator current angle estimator which determines the stator current angle Θαβ from the alpha-component and beta-component of the stator current vector. Several patterns repeat substantially every sixty degrees (<NUM>°) for the complex trigonometric equations used for phase current reconstruction. As such, the three hundred sixty degrees (<NUM>°) of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> can be partitioned into six sectors (Sector <NUM> to Sector <NUM>) of substantially sixty degree (<NUM>°) increments and the repeated patterns are related to the stator current angle Θαβ. Reference tables may be utilized to represent the patterns which allows preloading of the complex trigonometric calculation results for phase current reconstruction. In embodiments of the present disclosure, the appropriate reference table may selected in response to the estimated stator current angle Θαβ of the stator current vector and the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>. The reference tables themselves are indexed with respect to the stator current angle Θαβ and the sector of the stator current vector. The reference tables themselves include the reconstruction scaling factor utilized to reconstruct the respective phase current. In one embodiment, reconstruction of the respective phase current is accomplished in response to the reconstruction scaling factor and one of the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>.

<FIG> illustrates one example of half-bridge module 102a coupled to provide the phase current sense signal IPHU <NUM> to the system controller <NUM>. It should be appreciated that similarly named and numbered elements couple and function as described above. Further, only half-bridge module 102a is shown in <FIG>, but it should be appreciated that the coupling shown may also be utilized for half-bridge modules 102b and 102c.

The phase current sense signal IPHU <NUM> may be a current signal output by half-bridge module 102a to system controller <NUM>. The phase current sense signal IPHU <NUM> is representative of the drain current of the low-side power switch 110a and the negative values of the phase current IPHASEU <NUM>. Resistor <NUM> is coupled to return <NUM> and the terminal of the half-bridge module 102a which outputs the phase current sense signal IPHU <NUM>. The current signal output of the phase current sense signal IPHU <NUM> may be converted to voltage signal VIPHU 121via the resistor <NUM>. It should be appreciated that only half-bridge module 102a is shown in <FIG>, but it should be appreciated that resistors may be utilized to convert phase current sense signals output by half-bridge modules 102b,102c to voltage signals.

Previous techniques to provide feedback of the phase currents, IPHASEU <NUM>, IPHASEV <NUM>, IPHASEW <NUM>, included the use of shunt resistors in series with the low-side switch 110a, 110b, 110c of each leg of the half-bridge modules 102a, 102b, 102c. Additional components, such as an operational amplifier and offset components are also added for the system controller to receive the sensed phase currents, IPHASEU <NUM>, IPHASEV <NUM>, IPHASEW <NUM>, which utilizes significant physical space, increases component count, and overall system cost. For example, a total of twenty-nine components which are external from the half-bridge modules 102a, 102b, 102c, are utilized to provide the current feedback of the three phase currents IPHASEU <NUM>, IPHASEV <NUM>, IPHASEW <NUM> in previous solutions. By contrast, embodiments of the present disclosure include half-bridge modules 102a, 102b, 102c, which output phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> representative of the drain current of the low-side power switches 110a, 110b, 110c and therefore proportional to their respective phase currents. As such, a single resistor as shown in <FIG> per half-bridge module 102a, 102b, 102c may be utilized to provide feedback of the three phase currents IPHASEU, IPHASEV, IPHASEW, and reduces the external component count for current feedback by ninety percent. For the traditional shunt resistor, the entire phase current IPHASEU <NUM> flows through the shunt resistor and the power loss may be significant. In contrast, the internally provided phase current sense signal IPHU <NUM> by half-bridge module 102a is representative of the phase current IPHASEU <NUM> and is much smaller value, approximately <NUM>µA compared to the phase current IPHASEU <NUM> itself, which is approximately 1A. As such, power loss due to the traditional shunt resistor may be approximately 220mW while the power loss due to the phase current sense signal IPHU <NUM> may be approximately <NUM> mW, a <NUM>% improvement in power loss.

<FIG> illustrates diagram <NUM> of example phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> and diagram <NUM> of the corresponding example phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>. Phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> are substantially sinusoidal and shifted by one hundred twenty degrees (<NUM>°) from each other. For example, phase current IPHASEV <NUM> is shifted one hundred twenty degrees (<NUM>°) from phase current IPHASEU <NUM> while phase current IPHASEW <NUM> is shifted one hundred twenty degrees (<NUM>°) from phase current IPHASEV <NUM>. As such, phase current IPHASEW <NUM> is shifted two hundred forty degrees (<NUM>°) from phase current IPHASEU <NUM>. The x-axis of both diagrams <NUM> and <NUM> are representative of time and the stator current angle Θαβ. As shown, at zero degrees (<NUM>°) for stator current angle Θαβ substantially corresponds to the peak positive value of the phase current IPHASEU <NUM>, at one hundred twenty degrees (<NUM>°) for stator current angle Θαβ substantially corresponds to the peak positive value of phase current IPHASEV <NUM> while at two hundred forty degrees (<NUM>°) for stator current angle Θαβ substantially corresponds to the peak positive value of IPHASEW <NUM>. Each of phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> substantially have a period of substantially three hundred sixty degrees (<NUM>°).

Phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are representative of the negative values of their respective phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. Further, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are substantially constant for positive values of their respective phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. In one example, the constant value is substantially zero. However, in some implementations of the current sense circuits 115a, 115b, and 115c, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> have a minimum non-zero output value. As such, in one example, the constant value is the non-zero output value. However, it should be appreciated that the outputted phase current sense signal IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are positive for the sensed negative values of phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. As such, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are substantially a constant value for positive values of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>, respectively, and mirror the negative values of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>, respectively.

As shown in diagram <NUM>, phase current sense signal IPHU <NUM> is substantially the constant value from zero degrees (<NUM>°) to ninety degrees (<NUM>°). Between ninety degrees (<NUM>°) and two hundred seventy degrees (<NUM>°), the phase current sense signal IPHU <NUM> substantially mirrors the negative values of the phase current IPHASEU <NUM> between ninety degrees (<NUM>°) and two hundred seventy degrees (<NUM>°). Phase current sense signal IPHU <NUM> is substantially the constant value from two hundred seventy degrees (<NUM>°) to four hundred fifty degrees (<NUM>°).

Similarly, phase current sense signal IPHV <NUM> is substantially the constant value from thirty degrees (<NUM>°) to two hundred ten degrees (<NUM>°) and substantially mirrors the negative values of the phase current IPHASEV <NUM> between two hundred ten degrees (<NUM>°) and three hundred ninety degrees (<NUM>°). Phase current sense signal IPHW <NUM> is substantially the constant value between one hundred fifty degrees (<NUM>°) to three hundred thirty degrees (<NUM>°) and substantially mirrors the negative values of the phase current IPHASEW <NUM> between three hundred thirty degrees (<NUM>°) and five hundred ten degrees (<NUM>°). As such, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> are substantially the constant value for one hundred eighty-degree (<NUM>°) sections and mirror the negative values of their respective the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> for one hundred eighty-degree (<NUM>°) sections. Phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> also have a period of substantially three hundred sixty degrees (<NUM>°).

Shown in <FIG> are sectors <NUM> to <NUM>. Each sector is substantially in sixty-degree (<NUM>°) increments of the stator current angle Θαβ. Sector <NUM> corresponds with stator current angles Θαβ substantially between ninety degrees (<NUM>°) and one hundred fifty (<NUM>°) degrees. Sector <NUM> corresponds with stator current angles Θαβ substantially between one hundred fifty (<NUM>°) degrees and two hundred ten (<NUM>°) degrees. Sector <NUM> corresponds with stator current angles Θαβ substantially between two hundred ten (<NUM>°) degrees and two hundred seventy degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ substantially between two hundred seventy degrees (<NUM>°) and three hundred thirty (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ substantially between three hundred thirty (<NUM>°) and three hundred ninety degrees (<NUM>). Or in other words, sector <NUM> corresponds with stator current angles Θαβ substantially between three hundred thirty (<NUM>°) and three hundred sixty degrees (<NUM>°) and between zero degrees (<NUM>°) and thirty degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ substantially between thirty degrees (<NUM>°) and ninety degrees (<NUM>°).

<FIG> illustrates vector diagram <NUM> which corresponds with the timing diagrams shown in <FIG>. The degree markings in <FIG> corresponds with stator current angle Θαβ <NUM>, also shown with respect to <FIG>. The phase currents IPHASEU <NUM>, IPHASEV <NUM>, IPHASEW <NUM>, along with their respective phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>, may be represented as vectors, often referred to as current space vectors. The current space vector for a given winding has the direction representative of the magnetic field produced by that winding and a magnitude proportional to the phase current through the winding. The total stator current may be presented by a vector which is the sum of each current phase vector of each winding of the motor. Each current space vector of the three-phase motor is substantially one hundred twenty degrees (<NUM>°) apart.

The current space vectors of phase currents, IPHASEU, IPHASEV, IPHASEW allows for representation of the stator current in a three-axis reference frame of the motor windings. The three-axis reference frame of the motor windings are generally referred to as the U-axis, V-axis, and W-axis which are each one hundred twenty (<NUM>°) apart. As shown, the U-axis corresponds with zero degrees (<NUM>°), the V-axis corresponds with one hundred twenty degrees (<NUM>°), and the W-axis corresponds with two hundred forty degrees (<NUM>°). The phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>, provide the magnitude for the respective current space vectors representative of phase currents IPHASEU <NUM>, IPHASEV <NUM>, IPHASEW <NUM>. The direction of the current space vector representative of phase current IPHASEU <NUM> would be at zero degrees (<NUM>°), the direction of the current space vector representative of phase current IPHASEV <NUM> would be at one hundred twenty degrees (<NUM>°), and the direction of the current space vector representative of phase current IPHASEW <NUM> would be at two hundred forty degrees (<NUM>°). The individual current space vectors for each of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, IPHASEW <NUM> may be summed together to provide the stator current vector Iαβ <NUM>.

The representation of the stator current vector Iαβ <NUM> in the three-axis reference frame, U-axis, V-axis, and W-axis, can be translated to representation of the stator current vector Iαβ <NUM> in a two-axis reference frame of the stator. The two-axis reference frame of the stator is generally referred to as the alpha-axis (α-axis) and beta-axis (β-axis) which are ninety degrees (<NUM>°) apart. As shown, the alpha-axis (α-axis) corresponds with zero degrees (<NUM>°) while the beta-axis (β-axis) corresponds with ninety degrees (<NUM>°). A three-phase to two-phase transformation, such as the Clarke transform, may be utilized to translate the representation of the stator current vector Iαβ <NUM> in the three-axis reference frame (U-axis, V-axis, and W-axis) to the two-axis reference frame of the alpha-axis (α-axis) and beta-axis (β-axis).

<FIG> shows one example of the stator current vector Iαβ <NUM> which has a magnitude and a direction. The direction may be defined by the stator current angle Θαβ, which is the angular distance between the alpha-axis (α-axis) and the stator current vector Iαβ <NUM>. The stator current vector Iαβ <NUM> may be represented by an alpha-component vector, iα, and a beta-component vector, iβ. The alpha-component vector iα is substantially the projection of the stator current vector Iαβ <NUM> on the alpha-axis (α-axis) while the beta-component vector iβ is substantially the projection of the stator current vector Iαβ <NUM> on the beta-axis (β-axis). The sum of the alpha-component and beta-component would substantially equal the stator current vector Iαβ <NUM>.

Similar to <FIG>, the sectors <NUM> to <NUM> are shown by the shaded regions on vector diagram <NUM> of <FIG>. Each sector is substantially in sixty-degree (<NUM>°) increments of the stator current angle Θαβ. Sector <NUM> corresponds with stator current angles Θαβ substantially between ninety degrees (<NUM>°) and one hundred fifty (<NUM>°) degrees and is shown by the heavy-density dotted region. Sector <NUM> corresponds with stator current angles Θαβ substantially between one hundred fifty (<NUM>°) degrees and two hundred ten (<NUM>°) degrees and is shown by the light-density dotted region. Sector <NUM> corresponds with stator current angles Θαβ substantially between two hundred ten (<NUM>°) degrees and two hundred seventy degrees (<NUM>°) and is shown by the medium-density dotted region. Sector <NUM> corresponds with stator current angles Θαβ substantially between two hundred seventy degrees (<NUM>°) and three hundred thirty (<NUM>°) and is shown by the heavy-density dotted region. Sector <NUM> corresponds with stator current angles Θαβ substantially between three hundred thirty (<NUM>°) and three hundred sixty degrees (<NUM>°) and between zero degrees (<NUM>°) and thirty degrees (<NUM>°) and is shown by the light-density dotted region. Sector <NUM> corresponds with stator current angles Θαβ substantially between thirty degrees (<NUM>°) and ninety degrees (<NUM>°) and is shown by the medium-density dotted region.

As mentioned above, the stator current vector Iαβ <NUM> in the two-axis reference frame of the stator can be further represented by the rotating two-axis reference frame of the rotor. The rotating two-axis reference frame of the rotor is generally referred to as the direct-axis (d-axis) and quadrature-axis (q-axis) which are ninety degrees (<NUM>°) apart and rotate with respect to the two-axis reference frame of the stator. A stationary-to-rotating frame transformation, such as the Park transform, may be utilized to represent the stator current vector Iαβ <NUM> in terms of its direct-component on the d-axis and its quadrature-component on the q-axis. The direct-component of the stator current vector Iαβ <NUM> produces compression forces which does not turn the rotor while the quadrature-component of the stator current vector Iαβ <NUM> produces torque. Proportional-integral (PI) control could be utilized to minimize the direct-component and maximize the quadrature-component of the stator current vector Iαβ <NUM>.

As such, the representation of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, IPHASEW <NUM> as current space vectors may allow the utilization of control schemes, such as field oriented control, by the system controller <NUM>. However, as shown in <FIG>, the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> may not provide information regarding all of the phase currents IPHASEU <NUM>, IPHASEV <NUM>, IPHASEW <NUM> at the same time. For example, at substantially one hundred eighty degrees (<NUM>), only the phase current sense signal IPHU <NUM> is representative of its phase current IPHASEU <NUM>, and as such only information regarding the phase current IPHASEU <NUM> is available to the system controller <NUM>. As such, in embodiments of the present disclosure, system controller <NUM> utilizes phase current reconstruction.

In embodiments, the system controller <NUM> reconstructs the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> utilizing the stator current angle Θαβ <NUM> of the stator current vector Iαβ <NUM> and multiple reference tables. The system controller <NUM> further includes a stator current angle estimator which determines the stator current angle Θαβ <NUM> from the alpha-component iα and beta-component iβ of the stator current vector Iαβ <NUM>. Reference tables may be utilized and allows preloading of the complex trigonometric calculation results for phase current reconstruction. In one embodiment, these complex trigonometric calculation results represent a reconstruction scaling factor. In embodiments of the present disclosure, the appropriate reference table may selected in response to the estimated stator current angle Θαβ <NUM> of the stator current vector Iαβ <NUM> and one of the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>. The reference tables themselves are indexed with respect to the stator current angle Θαβ <NUM> and the sector of the stator current vector Iαβ <NUM>. In one embodiment, the stored values in the reference tables are representative of a reconstruction scaling factor and the reconstruction of the respective phase current IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM> is substantially the product of the stored reconstruction scaling factor provided by the appropriate reference table and the magnitude provided by one of the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>.

<FIG> illustrates one example system controller 306A with a phase current reconstructor <NUM>, in accordance with teachings of the present disclosure. System controller 306A is one example of system controller <NUM>, further, similarly named and numbered elements couple and function as described above. System controller 306A is shown including phase current reconstructor <NUM>, reference frame translator <NUM>, stator current estimator <NUM>, rotor position estimator <NUM>, proportional integrator (P-I) control <NUM>, reference frame translator <NUM>, and control signal generator <NUM>. The reference frame translator <NUM> is further shown as including a three-phase to two-phase transformer <NUM>, such as the Clarke transformer <NUM>, and a stationary-to-rotating frame transformer <NUM>, such as the Park transformer <NUM>. It should be appreciated that the system controller 306A shown in <FIG> may represent software architecture, hardware design, or a combination of both software architecture and hardware design. The system controller 306A shown in <FIG> implements field oriented control for the motor drive system, however, it should be appreciated that other control schemes may be utilized with the embodiments of the present disclosure. For example, a system controller utilizing sinusoidal commutation may take advantage of the reconstructed phase current magnitudes as discussed with embodiments of the present disclosure.

System controller 306A receives the phase current sense signals IPHU <NUM>, IPHV <NUM>, and IPHW <NUM> and outputs the control signals CTRLU <NUM>, CTRLV <NUM>, and CTROLW <NUM>. As shown, phase current reconstructor <NUM> receives phase current sense signals IPHU <NUM>, IPHV <NUM>, and IPHW <NUM> and the estimated stator current angle Θαβ <NUM>. In response to receiving the phase current sense signals IPHU <NUM>, IPHV <NUM>, and IPHW <NUM> and the estimated stator current angle Θαβ <NUM>, the phase current reconstructor <NUM> reconstructs the phase currents IPHASEU <NUM>, IPHASEV <NUM>, and IPHASEW <NUM>. The reconstructed phase currents are output by the phase current reconstructor <NUM> as a u-component iu <NUM>, a v-component iv <NUM>, and a w-component iw <NUM>. In one embodiment, the u-component iu <NUM> is representative of the reconstructed magnitude of phase current IPHASEU <NUM>, v-component iv <NUM> is representative of the reconstructed magnitude of phase current IPHASEV <NUM>, and w-component iw <NUM> is representative of the reconstructed magnitude of phase current IPHASEW <NUM>. It should be appreciated that the u-component iu <NUM>, a v-component iv <NUM>, and a w-component iw <NUM> may be referred to as the first reconstructed phase current magnitude iu, second reconstructed phase current magnitude iv, and third reconstructed phase current magnitude iw.

Phase current reconstructor <NUM> includes at least one reference table with preloaded values representative of reconstruction scaling factors. In one embodiment, the reconstructed phase current magnitudes, u-component iu <NUM>, v-component iv <NUM>, and w-component iw <NUM>, may be substantially the product of the appropriate stored reconstruction scaling factor and the magnitude provided by one of the phase current sense signals IPHU <NUM>, IPHV <NUM>, or IPHW <NUM>. Each reference table includes sixty values and the selection of the appropriate value to be outputted for the reconstruction scaling factor of the u-component iu <NUM>, v-component iv <NUM>, and w-component iw <NUM> is in response to the estimated stator current angle Θαβ <NUM>. Further, the preloaded values are computed based on the stator current angle Θαβ <NUM> and representative of the reconstruction scaling factor. As such, the reference tables are indexed with respect to the stator current angle Θαβ <NUM>. In embodiments of the present disclosure, the appropriate reference table may be selected in response to the estimated stator current angle Θαβ <NUM> and the phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM>. As will be further discussed, the reference table may be selected in response to the estimated stator current angle Θαβ <NUM> and which of the received phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> is available. The received phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> may be considered available or present if the received phase current sense signals IPHU <NUM>, IPHV <NUM>, IPHW <NUM> is greater than a threshold UMIN, VMIN, or WMIN, respectively. It should be appreciated that thresholds UMIN, VMIN, or WMIN may be referred to as the first threshold UMIN, second threshold VMIN and third threshold WMIN. In one example, the value of thresholds UMIN, VMIN, or WMIN are substantially equal. Reference frame translator <NUM> translates the reconstructed phase current magnitudes, u-component iu <NUM>, v-component iv <NUM>, and w-component iw <NUM> from the three-axis reference frame of the motor windings to the corresponding direct-component id <NUM> and quadrature-component iq <NUM> related to the rotating two-axis reference frame of the rotor. As shown, the three-phase to two-phase transformer <NUM>, e.g. Clarke transformer <NUM>, of reference frame translator <NUM> receives the u-component iu <NUM>, v-component iv <NUM>, and w-component iw <NUM> and outputs the alpha-component iα <NUM> and beta-component iβ <NUM> related to the two-axis reference frame of the stator. The alpha-component iα <NUM> and beta-component iβ <NUM> are the magnitudes of the projection of the stator current vector Iαβ on the α-axis and β-axis, respectively. In one example operation, three-phase to two-phase transformer <NUM>, Clarke transformer <NUM>, performs the Clarke transformation to the u-component iu <NUM>, v-component iv <NUM>, and w-component iw <NUM> to output the alpha-component iα <NUM> and beta-component iβ <NUM>.

Stator current angle estimator <NUM> receives the alpha-component iα <NUM> and beta-component iβ <NUM> and outputs the estimated stator current angle Θαβ <NUM>. As mentioned above, the summation of the alpha-component iα <NUM> and beta-component is <NUM> results in the stator current vector Iαβ <NUM>. As such, the stator current angle Θαβ <NUM> may be derived from the alpha-component iα <NUM> and beta-component iβ <NUM>. In one example, and further shown with respect to <FIG>, a phase-locked loop (PLL) may be utilized to determine the estimated stator current angle Θαβ <NUM> from the alpha-component iα <NUM> and beta-component iβ <NUM>. However, it should be appreciated that other angle estimators may be utilized. For example, an arctangent angle estimator utilizing the standard C library or an arctangent angle estimator utilizing special hardware.

Rotor position estimator <NUM> is also coupled to receive the alpha-component iα <NUM> and beta-component iβ <NUM> and outputs the rotor angle Θrotor <NUM>. In one example, the rotor position estimator <NUM> determines the angular position of the rotor flux vector (e.g. rotor angle Θrotor <NUM>). In one example of the present disclosure, the system controller 306A is sensorless and does not use an external sensor to determine the position of the rotor. As such, the system controller 306A includes the rotor position estimator <NUM>. In one example, the rotor position estimator <NUM> determines the rotor angle Θrotor <NUM> in response to the alpha-component iα <NUM> and beta-component iβ <NUM>, along with the control signals vα <NUM> and vβ <NUM> produced by the reference frame translator <NUM>. As will be further discussed, control signal vα <NUM> is outputted to regulate the alpha-component iα <NUM> while the control signal vβ <NUM> is outputted to regulate the beta-component iβ <NUM> to the desired values. Although, it should be appreciated that embodiments of the present disclosure may be implemented external rotor position sensors. In one embodiment, the rotor flux vector is substantially ninety degrees (<NUM>°) behind the stator current vector Iαβ <NUM>.

The stator current angle estimator <NUM> may need time to initialize to provide a more accurate estimated stator current angle Θαβ <NUM>. In particular, the stator current angle estimator <NUM> may be initialized during a start-up operation of the motor drive system and system controller 306A. However, the rotor flux vector is substantially ninety degrees (<NUM>°) behind the stator current vector Iαβ <NUM>. As such, during the start-up operation, the phase current reconstructor <NUM> may utilize the rotor angle Θrotor <NUM> to determine the stator current angle Θαβ rather than the estimated stator current angle Θαβ <NUM> provided by the stator current angle estimator <NUM>. In the embodiment shown, the phase current reconstructor <NUM> receives the rotor angle Θrotor <NUM>. During the start-up operation, the phase current reconstructor <NUM> determines that the stator current angle Θαβ <NUM> is substantially the sum of the rotor angle Θrotor <NUM> and a preset offset angle Θangle. In one example, the preset offset angle Θangle is substantially ninety degrees (<NUM>°). As such, during the start-up operation, the stator current angle Θαβ <NUM> varies between zero degrees (<NUM>°) and three hundred sixty degrees (<NUM>°) at a predetermined rate to output the u-component iu <NUM>, v-component iv <NUM>, and w-component iw <NUM>. Once start-up operation is completed, the phase current reconstructor <NUM> utilizes the estimated stator current angle Θαβ <NUM> provided by the stator current angle estimator <NUM>.

A stationary-to-rotating frame transformer <NUM>, e.g. the Park transformer <NUM>, receives the alpha-component iα <NUM>, beta-component iβ <NUM> corresponding to the fixed two-axis reference frame of the stator, and the rotor angle Θrotor <NUM>, and outputs the direct-component id <NUM> and quadrature-component iq <NUM> corresponding to the rotating two-axis reference frame of the rotor. In one example operation, the stationary-to-rotating frame transformer <NUM>, e.g. Park transformer <NUM>, performs the Park transformation to the alpha-component iα, <NUM> and beta-component iβ <NUM> to output the direct-component id <NUM> and quadrature-component iq <NUM>.

P-I control block <NUM> receives the direct-component id <NUM> and quadrature-component iq <NUM> and outputs the control signal vd <NUM> and control signal vq <NUM>. The P-I control block <NUM> also receives user input <NUM>. In one embodiment, user input <NUM> is representative of the desired mechanical output of the motor, such as the speed, the torque, or the position of the motor. In one example, the user input <NUM> may be representative of the torque of the motor. The direct-component id <NUM> is representative of compression forces of the motor while the quadrature-component iq <NUM> is representative of the torque of the motor. The P-I control block <NUM> may utilize two P-I controllers, one each for the direct-component id <NUM> and the quadrature-component iq <NUM>. In operation, one P-I controller of the P-I control block <NUM> determines the value for the control signal vd <NUM> such that the direct-component id <NUM> is regulated to a desire value. As such, the control signal vd <NUM> is representative of the regulation of the direct-component id <NUM> to the desired value. In one embodiment, the P-I control block <NUM> minimizes the direct-component id <NUM> to substantially zero. The other P-I controller of the P-I control block <NUM> determines the value for the control signal vq <NUM> such that the quadrature-component iq <NUM> is regulated to the desired torque of the motor indicated by the user input <NUM>. As such, the control signal vq <NUM> is representative of the regulation of the quadrature-component iq <NUM> to the desired value.

Reference frame translator <NUM> receives the control signal vq <NUM> and control signal vq <NUM> and outputs the control signal vu <NUM>, control signal vv <NUM>, and the control signal vw <NUM>. Reference frame translator <NUM> translates the control signal vd <NUM> and control signal vq <NUM> of the rotating two-axis reference frame of the rotor to the corresponding control signal vu <NUM>, control signal vv <NUM>, and the control signal vw <NUM> of the three-axis reference frame of the motor windings. In one example, the reference frame translator <NUM> could perform the inverse Park transform followed by the inverse Clarke transform to output the control signal vu <NUM>, control signal vv <NUM>, and the control signal vw <NUM>. However, it should be appreciated that there are other techniques for determining the corresponding control signal vu <NUM>, control signal vv <NUM>, and the control signal vw <NUM> from the control signal vd <NUM> and control signal vq <NUM>. For example, space vector modulation may also be used. In one example, the control signal vu <NUM> is representative of the value to regulate the u-component iU <NUM> (e.g. magnitude of phase current IPHASEU), the control signal vv <NUM> is representative of the value to regulate the v-component iv <NUM> (e.g. magnitude of phase current IPHASEV), and the control signal vw <NUM> is representative of the value to regulate the w-component iw <NUM> (e.g. magnitude of phase current IPHASEW). It should be appreciated that, similar to reference frame translator <NUM>, reference frame translator <NUM> performs a two-step transformation from the rotating two-axis reference frame of the rotor to the two-axis reference frame of the stator followed by a transformation to the three-axis reference frame of the motor windings. As such, the reference frame translator <NUM> generates control signal vα <NUM>, representative of the value to regulate the alpha-component iα <NUM> to the desired value, and control signal vβ <NUM>, representative of the value to regulate the beta-component iβ <NUM> to the desired value.

Control signal generator <NUM> receives control signal vu <NUM>, vv <NUM>, and vw <NUM> and in response, outputs the control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> to their respective half-bridge modules. For example, the control signal generator <NUM> can output control signal CTRLU <NUM> in response to the control signal vu <NUM>, outputs the control signal CTRLV <NUM> in response to control signal vv <NUM>, and outputs the control signal CTRLW <NUM> in response to control signal vw <NUM>. In operation, the control signal generator <NUM> may perform pulse width modulation (PWM) to output the control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> in response to control signals vu <NUM>, vv <NUM>, and vw <NUM>. In one example, control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> are rectangular pulse width waveforms with varying lengths of high and low durations. A low value for control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> could correspond with turning ON the respective high-side switch and turning OFF the respective low-side switch. A high value for control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> could correspond with turning ON the respective low-side switch and turning OFF the respective high-side switch, or vice versa. The durations of the high and low sections of the control signals CTRLU <NUM>, CTRLV <NUM>, and CTRLW <NUM> may be computed in response to receiving the control signals vu <NUM>, vv <NUM>, and vw <NUM>.

In one example, the system controller 306A, phase current reconstructor <NUM>, and stator current angle estimator <NUM> can be implemented by dedicated logic circuitry or a microcontroller executing computer-executable instructions, such as a <NUM> Cortex-MO microcontroller. These microcontrollers generally have about <NUM>-<NUM> kB flash memory, about <NUM>-<NUM> kB of RAM, with a processing speed of about <NUM>. For example, software may be utilized to program a microcontroller utilized for system controller 306A.

<FIG> illustrates another example system controller 306A with a phase current reconstructor <NUM>, in accordance with teachings of the present disclosure. System controller 306B is one example of system controller <NUM> and shares many similarities with system controller 306A, and similarly named and numbered elements couple and function as described above. At least one difference, however, is system controller 306B implements a pseudo field oriented control and there is no stationary-to-rotating transformation for the reference frame translator <NUM>. However, it should be appreciated that the phase current reconstructor <NUM> and the stator current angle estimator <NUM> couple and function as described above with respect to <FIG>.

The reference frame translator <NUM> includes the three-phase to two-phase transformer <NUM>, e.g. the Clarke transformer. As shown, the three-phase to two-phase transformer <NUM> receives the u-component iu <NUM>, v-component iv <NUM>, and w-component iw <NUM>, representative of the reconstructed phase current magnitudes, and outputs the alpha-component iα <NUM> and beta-component iβ <NUM> related to the two-axis reference frame of the stator. The alpha-component iα <NUM> and beta-component iβ <NUM> are the magnitudes of the projection of the stator current vector Iαβ on the α-axis and β-axis, respectively. Stator current angle estimator <NUM> receives the alpha-component iα <NUM> and beta-component iβ <NUM> and outputs the estimated stator current angle Θαβ <NUM>.

In the example system controller 306A shown in <FIG>, the P-I control block <NUM> receives the quadrature-component iq <NUM> and direct-component id <NUM>. However, for the system controller 306B shown in <FIG>, the P-I control block <NUM> receives the rotor angle Θrotor <NUM>. As described above, the rotor position estimator <NUM> determines the angular position of the rotor flux vector (e.g. rotor angle Θrotor <NUM>). In the example shown in <FIG>, the P-I control block <NUM> determines the control signal vq <NUM> in response to the user input <NUM>, representative of the regulation of the quadrature-component of the motor. The control signal vd <NUM>, representative of the regulation of the direct component of the motor, is substantially zero. P-I control block <NUM> also estimates and regulates the speed of the motor in response to the rotor angle Θrotor <NUM>.

<FIG> illustrates a stator current angle estimator <NUM>, which is one example of stator current angle estimator <NUM>, and it should be appreciated that similarly named and numbered elements couple and function as described above. Stator current angle estimator <NUM> is shown as including a multiplier <NUM>, multiplier <NUM>, arithmetic operator <NUM>, amplifier KP <NUM>, amplifier Ki <NUM>, integrator <NUM>, arithmetic operator <NUM>, integrator <NUM>, cosine <NUM>, and sine <NUM>.

The stator current angle estimator <NUM> receives the alpha-component iα <NUM> and beta-component iβ <NUM> of the stator current vector Iαβ and outputs the estimated stator current angle Θαβ <NUM>. Multiplier <NUM> is coupled to receive the beta-component iβ <NUM> and the cosine of estimated stator current angle Θαβ <NUM>. The output of multiplier <NUM> is substantially the product of the beta-component iβ <NUM> and the cosine of estimated stator current angle Θαβ <NUM>, or mathematically: iβ cos(Θaβ). Multiplier <NUM> is coupled to receive the alpha-component iα <NUM> and the sine of estimated stator current angle Θαβ <NUM> and its output is substantially the product of the alpha-component iα <NUM> and the sine of estimated stator current angle Θαβ <NUM>, or mathematically: iα sin(Θαβ).

The outputs of multiplier <NUM> and multiplier <NUM> are received at arithmetic operator <NUM>. As shown, arithmetic operator <NUM> performs subtraction and outputs the difference between the outputs of multiplier <NUM> and <NUM>, or mathematically: iβ cos(Θαβ) - iα sin(Θαβ). Amplifiers <NUM> and <NUM> are coupled to receive the output of the arithmetic operator <NUM> and amplify the output of the arithmetic operator <NUM> by its gain, KP and Ki, respectively. An integrator <NUM> receives and integrates the output of amplifier Ki.

Arithmetic operator <NUM> is coupled to receive the output of amplifier <NUM> and integrator <NUM>. As shown, arithmetic operator <NUM> is an adder and its output is the sum of the output of amplifier <NUM> and integrator <NUM>. Integrator <NUM> is coupled to receive and integrate the output of arithmetic operator <NUM>. The output of integrator <NUM> is the estimated stator current angle Θαβ <NUM>. Cosine block <NUM> is coupled to receive the estimated stator current angle Θαβ <NUM> and output the cosine of stator current angle Θαβ <NUM> to multiplier <NUM>. Similarly, sine block <NUM> is coupled to receive the estimated stator current angle Θαβ <NUM> and output the sine of stator current angle Θαβ <NUM> to multiplier <NUM>.

5A illustrates a flow diagram <NUM> of one example method of phase current reconstruction by a system controller. The example process can be performed by a phase current reconstructor programmed in accordance with this specification, e.g., the phase current reconstructor shown in <FIG>. It should be appreciated that the u-component iu, v-component iv, and w-component iw are representative of the magnitudes of the reconstructed phase currents for phase currents IPHASEU, IPHASEV, and IPHASEW, respectively.

At block <NUM>, the phase current sense signals IPHU, IPHV, and IPHW are received. The process proceeds to decision block <NUM>. At decision block <NUM>, phase current sense signal IPHU is compared to threshold UMIN and phase current sense signal IPHV is compared to threshold VMIN. If the phase current sense signal IPHU is greater than threshold UMIN and phase current sense signal IPHV is greater than VMIN, the process proceeds to block <NUM>. At block <NUM>, the reconstructed magnitudes of the phase currents, u-component iu, v-component iv, and w-component iw, may be determined from phase current sense signals IPHU and IPHV. At block <NUM>, the u-component iU is substantially the negative value of phase current sense signal IPHU (iU = -IPHU), the v-component iv is substantially the negative value of phase current sense signal IPHV (iV = -IPHV), and the w-component iw is substantially the sum of phase current sense signal IPHU and phase current sense signal IPHV (iW = IPHU + IPHV). The process then continues to block <NUM> and the determined reconstructed phase current magnitudes, u-component iU, v-component iv, and w-component iw are outputted.

If either or both the phase current sense signal IPHU or the phase current sense signal IPHV is less than their respective thresholds UMIN or VMIN, the process proceeds to decision block <NUM>. At decision block <NUM>, phase current sense signal IPHU is compared to threshold UMIN and phase current sense signal IPHW is compared to threshold WMIN. If the phase current sense signal IPHU is greater than threshold UMIN and phase current sense signal IPHW is greater than WMIN, the process proceeds to block <NUM>. At block <NUM>, the reconstructed magnitudes of the phase currents, u-component iu, v-component iv, and w-component iw may be determined from phase current sense signals IPHU and IPHW. At block <NUM>, the u-component iU is substantially the negative value of phase current sense signal IPHU (iU = -IPHU), the w-component iw is substantially the negative value of phase current sense signal IPHW (iW = -IPHW), and the v-component iv is substantially the sum of phase current sense signal IPHU and phase current sense signal IPHW (iV = IPHU + IPHW). The process then continues to block <NUM> and the determined reconstructed phase current magnitudes, u-component iu, v-component iv, and w-component iw are outputted.

If either or both the phase current sense signal IPHU or the phase current sense signal IPHW is less than their respective thresholds UMIN or WMIN, the process proceeds to decision block <NUM>. At decision block <NUM>, phase current sense signal IPHV is compared to threshold VMIN and phase current sense signal IPHW is compared to threshold WMIN. If the phase current sense signal IPHV is greater than threshold VMIN and phase current sense signal IPHW is greater than WMIN, the process proceeds to block <NUM>. At block <NUM>, the reconstructed magnitudes of the phase currents, u-component iu, v-component iv, and w-component iw may be determined from phase current sense signals IPHV and IPHW. At block <NUM>, the v-component iv is substantially the negative value of phase current sense signal IPHV (iV = -IPHV), the w-component iw is substantially the negative value of phase current sense signal IPHW (iW = -IPHW), and the u-component iU is substantially the sum of phase current sense signal IPHV and phase current sense signal IPHW (iU = IPHV + IPHW). The process then continues to block <NUM> and the determined reconstructed phase current magnitudes, u-component iu, v-component iv, and w-component iw are outputted.

Thresholds UMIN, threshold VMIN, and threshold WMIN are offset thresholds and are thresholds utilized to check for the presence of the phase current sense signals IPHU, IPHV, and IPHW. In one embodiment, the phase current sense signals IPHU, IPHV, and IPHW have a minimum constant value even when no current is flowing through the low-side power switches of the half-bridge modules. As such, the thresholds UMIN, VMIN, and WMIN may be selected to disregard the minimum constant value. Further, the thresholds UMIN, VMIN, and WMIN may be utilized for noise rejection. In one example, the value of thresholds UMIN, VMIN, or WMIN are substantially equal.

If either or both the phase current sense signal IPHV or the phase current sense signal IPHW is less than their respective thresholds VMIN or WMIN, the process proceeds to decision block <NUM>. If the process proceeds to decision block <NUM>, one of phase current sense signals IPHU, IPHV, or IPHW is greater than their respective thresholds UMIN, VMIN, or WMIN while the other two-phase current sense signals are less than their respective thresholds UMIN, VMIN, or WMIN. When only one of the phase current sense signals is greater than their respective threshold, the phase current reconstructor utilizes reference tables and an estimated stator current angle Θαβ to reconstruct the phase current and determine the reconstructed phase current magnitudes, u-component iu, v-component iv, and w-component iw.

At decision block <NUM>, it is determined if start-up operation is complete for the motor drive system. If start-up operation is not completed, the process proceeds to block <NUM> and the phase current reconstructor receives the rotor angle Θrotor and a preset offset angle Θoffset to determine the stator current angle Θαβ. In one example, the stator current angle Θαβ is substantially the sum of the rotor angle Θrotor and the preset offset angle Θoffset, or mathematically: Θaβ = Θrotor + Θoffset. The preset offset angle Θoffset may be substantially ninety degrees (<NUM>°) and is representative of the angular distance which the rotor flux vector is behind the stator current vector. The stator current angle Θαβ determined from the rotor angle Θrotor and the preset offset angle Θoffset is utilized by the phase current reconstructor to reconstruct the phase current magnitudes, u-component iu, v-component iv, and w-component iw. If the start-up operation is completed, the process proceeds to block <NUM> and the phase current reconstructor receives the estimated stator current angle Θαβ from the stator current angle estimator. The estimated stator current angle Θαβ from the is utilized by the phase current reconstructor to reconstruct the phase current magnitudes, u-component iu, v-component iv, and w-component iw.

From block <NUM> or <NUM>, the process proceeds to block <NUM>. At block <NUM>, the phase current reconstructor determines which of the phase current sense signals IPHU, IPHV, or IPHW is available. In other words, the phase current reconstructor determines which of the phase current sense signals IPHU, IPHV, and IPHW is greater than its respective threshold UMIN, VMIN, and WMIN. For whichever of the phase current sense signals IPHU, IPHV, or IPHW is determined to be present, its corresponding reconstructed phase current magnitude iu, iv, or iw is substantially the negative value of the available phase current signal. For example, if phase current sense signal IPHU is present, its corresponding u-component iU (e.g. the reconstructed phase current magnitude) is substantially the negative of phase current sense signal IPHU, or mathematically: iU = -IPHU. If phase current sense signal IPHV is present, its corresponding v-component iv (e.g. the reconstructed phase current magnitude) is substantially the negative of phase current sense signal IPHV, or mathematically: iV = -IPHV. If phase current sense signal IPHW is present, its corresponding w-component iw (e.g. the reconstructed phase current magnitude) is substantially the negative of phase current sense signal IPHW, or mathematically: iW = -IPHW. Once the available phase current sense signal is determined and the corresponding reconstructed phase current magnitude is determined, the process proceeds to block <NUM>.

At block <NUM>, the appropriate sector is selected. As mentioned above with respect to <FIG>, the three hundred sixty degrees (<NUM>°) period can be sectioned into six sectors of substantially sixty-degree (<NUM>°) increments. The sector is selected in response to the value of the determined or estimated stator current angle Θαβ provided from block <NUM> or <NUM>. For example, a stator current angle Θαβ equal to eighty-five degrees (<NUM>°) would correspond to sector <NUM>.

In one example, sector <NUM> corresponds with stator current angles Θαβ from ninety degrees (<NUM>°) to one hundred forty-nine degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ from one hundred fifty (<NUM>°) degrees to two hundred nine (<NUM>°) degrees. Sector <NUM> corresponds with stator current angles Θαβ from two hundred ten (<NUM>°) degrees to two hundred sixty-nine degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ from two hundred seventy degrees (<NUM>°) to three hundred twenty-nine degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ from three hundred thirty (<NUM>°) to three hundred sixty degrees (<NUM>°) and from zero degrees (<NUM>°) to twenty-nine degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ from thirty degrees (<NUM>°) to eighty-nine degrees (<NUM>°).

Once the sector has been determined, the sector angle Θsector can also be determined. The sector angle Θsector corresponds with the first occurring degree in a sector from the counterclockwise direction. As will be further discussed, the stator current angle Θαβ, along with the sector angle Θsector are used to determine the index Θindex for the appropriate reference table. The index Θindex is used to determine which stored value representative of the reconstruction scaling factor in the reference table is used for the appropriate u/v/w-component. The sector and corresponding sector angle Θsector are shown in Table <NUM> below:.

Once the sector is determined, the appropriate reference tables may be selected in response to the sector, the stator current angle Θαβ, and which one of the phase current sense signal IPHU, IPHV, or IPHW is available. <FIG> and <FIG> illustrate examples for determining the appropriate reference table for phase current reconstruction. It should be appreciated that since only one of phase current sense signal IPHU, IPHV, or IPHW is available, two reference tables are selected for the other two motor windings which are not available.

The process then proceeds to block <NUM>. The stator current angles Θαβ, along with the sector angle Θsector, are utilized to determine the index Θindex for the appropriate reference tables to determine the stored value representative of the reconstruction scaling factors for the reconstructed phase current magnitudes, u-component iU, v-component iv, and/or the w-component iw. As will be discussed, the index Θindex is the difference between the stator current angles Θαβ and the sector angle Θsector, or mathematically: Θindex = Θαβ - Θsector.

For example, if phase current sense signal IPHU is available, reference tables are selected to determine the scaling factors which are utilized to reconstruct the phase current magnitudes, v-component iv and w-component iw. corresponding with phase currents, IPHASEV and IPHASEW, respectively. Both reference tables are selected in response to the sector determined from the stator current angles Θαβ. Further, if the stator current angle Θαβ is eighty-five degrees (<NUM>°), the sector would be sector <NUM>, the sector angle Θsector is thirty degrees (<NUM>°) and the index Θindex is fifty-five degrees (<NUM>°). As such, an index Θindex of fifty-five degrees (<NUM>°) is utilized to determine the location for the scaling factors in their corresponding reference tables to be used to reconstruct the phase current magnitudes, v-component iV and w-component iw.

Once the scaling factors are selected, the process proceeds to block <NUM> and the reconstructed phase current magnitudes, u-component iU, v-component iv and w-component iw are determined from the scaling factors and which of the phase current sense signals IPHU, IPHV, or IPHW is available. It should be appreciated that for the reconstructed phase current magnitudes in which the corresponding phase current sense signal is not available, the reconstructed phase current magnitude is substantially the product of the selected scaling factor from the appropriate reference table and the available phase current sense signal. For example, if the phase current sense signal IPHU is available and phase current sense signals IPHV and IPHW are not available, the reconstructed phase current magnitudes, v-component iv and w-component iw is substantially the product of the appropriate scaling factor and the phase current sense signal IPHU. For example, the reconstructed phase current magnitude, v-component iv, is substantially the product of the selected scaling factor from step <NUM> and phase current sense signal IPHU. Similarly, the reconstructed phase current magnitude, w-component iw, is substantially the product of the selected scaling factor from step <NUM> and phase current sense signal IPHU. The reconstructed phase current magnitude, u-component iU, corresponds with the negative of the phase current sense signal IPHU, or mathematically: iU = -IPHU.

Once the reconstructed phase current magnitudes, u-component iU, v-component iv, and/or the w-component iw are determined, the process proceeds to block <NUM> and the phase current reconstructor outputs the u-component iU, v-component iv, and/or the w-component iw. It should be appreciated that the u-component iu is representative of the magnitude of phase current IPHASEU, v-component iv is representative of the magnitude of phase current IPHASEV, and w-component iw is representative of the magnitude of phase current IPHASEW.

<FIG> illustrates table <NUM> which shows one example process for selecting the reconstruction reference table in response to the stator current angle Θαβ and which one of the phase current sense signal IPHU, IPHV, or IPHW is available. As mentioned above, the sector and sector angle Θsector are determined from the stator current angle Θαβ. Once the sector is determined, the appropriate reference table is selected in response to which of the phase current sense signals IPHU, IPHV, IPHW are available. In other words, the phase current reconstructor determines which of the phase current sense signals IPHU, IPHV, and IPHW is greater than its respective threshold UMIN, VMIN, and WMIN.

For the example shown, sector <NUM> corresponds with stator current angles Θαβ from ninety degrees (<NUM>°) to one hundred forty-nine degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ from one hundred fifty (<NUM>°) degrees to two hundred nine (<NUM>°) degrees. Sector <NUM> corresponds with stator current angles Θαβ from two hundred ten (<NUM>°) degrees to two hundred sixty-nine degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ from two hundred seventy degrees (<NUM>°) to three hundred twenty-nine degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ from three hundred thirty (<NUM>°) to three hundred sixty degrees (<NUM>°) and from zero degrees (<NUM>°) to twenty-nine degrees (<NUM>°). Sector <NUM> corresponds with stator current angles Θαβ from thirty degrees (<NUM>°) to eighty-nine degrees (<NUM>°).

Referring to the first row corresponding to sector <NUM> for stator current angles Θαβ from ninety to one hundred forty-nine degrees (<NUM>°-<NUM>°). If phase current sense signal IPHU is available for sector <NUM>, reference table A is utilized to determine the scaling factor for the w-component iw to reconstruct the phase current IPHASEW. As mentioned above, the w-component iw is representative of the magnitude of phase current IPHASEW <NUM>, and is substantially the product of the scaling factor selected from reference table A and the phase current sense signal IPHU. Further, reference table B is utilized to determine the scaling factor for the v-component iv to reconstruct the phase current IPHASEV, the v-component iv is representative of the magnitude of phase current IPHASEV and is substantially the product of the scaling factor selected from reference table B and the phase current sense signal IPHU.

If phase current sense signal IPHW is available for sector <NUM>, reference table A' is utilized to determine the scaling factor of the u-component iu to reconstruct the phase current IPHASEU, the u-component iU is representative of the magnitude of phase current IPHASEU and is substantially the product of the scaling factor selected from reference table A' and the phase current sense signal IPHW. Further, reference table B' is utilized to determine the value for the v-component iv to reconstruct the phase current IPHASEV, the v-component iv is representative of the magnitude of phase current IPHASEV and is substantially the product of the scaling factor selected from reference table B' and the phase current sense signal IPHW.

As shown in <FIG>, in one embodiment, the phase current reconstructor utilizes three reference tables, reference tables A, B, and C. These reference tables may also be referred to as the first reference table (A), second reference table (B) and third reference table (C). The table <NUM> also illustrates reference tables A', B' and C'. These reference tables may also be referred to as the reverse first reference table (A'), reverse second reference table (B') and reverse third reference table (C'). Reference tables A', B', and C' substantially correspond with reference tables A, B, and C, however, are indexed in reverse from reference tables A, B, and C. As mentioned above, the index Θindex for references tables is substantially the difference between the stator current angles Θαβ and the sector angle Θsector, or mathematically: Θindex = Θαβ - Θsector. As such, the index Θindex has sixty values and varies from <NUM> degrees to fifty-nine degrees (<NUM>°-<NUM>°).

For example, a prestored value representative of scaling factors to reconstruct the phase current magnitudes is stored in reference table A at a location corresponding to index Θindex at zero degrees (<NUM>°). The same prestored value is stored in reverse in reference table A'. For example, the prestored value is stored at a location corresponding to index Θindex at fifty-nine degrees (<NUM>°) in reference table A'. A prestored value is stored in reference table A at a location corresponding to index Θindex at one degree (<NUM>°). The same prestored value is stored at a location corresponding to index Θindex at fifty-eight degrees (<NUM>°) in reference table A', and so on and so forth. This indexing is similar for reference table B with reference table B', and reference table C and reference table C'.

If the phase current sense signal IPHV is available for sector <NUM>, reference table C is utilized to determine the value of the u-component iu to reconstruct the phase current IPHASEU, the u-component iU is representative of the magnitude of phase current IPHASEU and is substantially the product of the scaling factor selected from reference table C and the phase current sense signal IPHV. Further, reference table C' is utilized to determine the value for the w-component iw to reconstruct the phase current IPHASEW, the w-component iw is representative of the magnitude of phase current IPHASEW and is substantially the product of the scaling factor selected from reference table C' and the phase current sense signal IPHV. However, these sections of the <NUM> are grayed out, as generally in sector <NUM>, it is phase current sense signals IPHU and IPHW which are available.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from one hundred fifty to two hundred nine degrees (<NUM>°-<NUM>°). If phase current sense signal IPHU is available for sector <NUM>, reference table C is utilized to determine the scaling factor for the w-component iw and the w-component iw is substantially the product of the scaling factor selected from reference table C and the phase current sense signal IPHU. Further, reference table C' is utilized to determine the scaling factor for the v-component iv and the v-component iv is substantially the product of the scaling factor selected from reference table C' and the phase current sense signal IPHU.

If phase current sense signal IPHW is available for sector <NUM>, reference table B is utilized to determine the scaling factor of the u-component iu to reconstruct the phase current IPHASEU. Further, reference table A is utilized to determine the scaling factor for the v-component iv to reconstruct the phase current IPHASEV. If phase current sense signal IPHV is available for sector <NUM>, reference table B' is utilized to determine the scaling factor of the u-component iu and reference table A' is utilized to determine the scaling factor for the w-component iw. However, these sections of the <NUM> are grayed out, as generally in sector <NUM>, it is phase current sense signals IPHU which is available.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from two hundred ten to two hundred sixty-nine degrees (<NUM>°-<NUM>°). If phase current sense signal IPHU is available for sector <NUM>, reference table B' is utilized to determine the scaling factor for the w-component iw and reference table A' is utilized to determine the scaling factor for the v-component iv. The w-component iw is substantially the product of the scaling factor selected from reference table B' and the phase current sense signal IPHU and the v-component iv is substantially the product of the scaling factor selected from reference table A' and the phase current sense signal IPHU. If phase current sense signal IPHV is available for sector <NUM>, reference table A is utilized to determine the scaling factor of the u-component iu and reference table B is utilized to determine the scaling factor for the w-component iw. The u-component iu is substantially the product of the scaling factor selected from reference table A and the phase current sense signal IPHV and the w-component iw is substantially the product of the scaling factor selected from reference table B and the phase current sense signal IPHV.

If phase current sense signal IPHW is available for sector <NUM>, reference table C' is utilized to determine the scaling factor of the u-component iu and reference table C is utilized to determine the scaling factor for the v-component iv. However, these sections of the <NUM> are grayed out, as generally in sector <NUM>, it is phase current sense signals IPHU and IPHV which are available.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from two hundred seventy to three hundred twenty-nine (<NUM>°-<NUM>°). If phase current sense signal IPHV is available for sector <NUM>, reference table C is utilized to determine the value of the u-component iu and reference table C' is utilized to determine the value for the w-component iw. The u-component iu is substantially the product of the scaling factor selected from reference table C and the phase current sense signal IPHV and the w-component iw is substantially the product of the scaling factor selected from reference table C' and the phase current sense signal IPHV.

If phase current sense signal IPHU is available for sector <NUM>, reference table A is utilized to determine the scaling factor for the w-component iw and reference table B is utilized to determine the scaling factor for the v-component iv. If phase current sense signal IPHW is available for sector <NUM>, reference table A' is utilized to determine the scaling factor of the u-component iu and reference table B' is utilized to determine the scaling factor for the v-component iv. However, these sections of the <NUM> are grayed out, as generally in sector <NUM>, it is phase current sense signals IPHV which is available.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from three hundred thirty to three hundred fifty-nine and zero to twenty nine degrees (<NUM>°-<NUM>°; <NUM>°-<NUM>°). If phase current sense signal IPHW is available for sector <NUM>, reference table B is utilized to determine the scaling factor of the u-component iu and reference table A is utilized to determine the scaling factor for the v-component iv. The u-component iu is substantially the product of the scaling factor selected from reference table B and the phase current sense signal IPHW and the v-component iv is substantially the product of the scaling factor selected from reference table A and the phase current sense signal IPHW. If phase current sense signal IPHV is available for sector <NUM>, reference table B' is utilized to determine the scaling factor of the u-component iu and reference table A' is utilized to determine the scaling factor for the w-component iw. The u-component iu is substantially the product of the scaling factor selected from reference table B' and the phase current sense signal IPHV and the w-component iw is substantially the product of the scaling factor selected from reference table A' and the phase current sense signal IPHV.

If phase current sense signal IPHU is available for sector <NUM>, reference table C is utilized to determine the scaling factor for the w-component iw and reference table C' is utilized to determine the scaling factor for the v-component iv. However, these sections of the <NUM> are grayed out, as generally in sector <NUM>, it is phase current sense signals IPHW and IPHV which are available.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from thirty to eighty-nine degrees (<NUM>°-<NUM>°). If phase current sense signal IPHW is available for sector <NUM>, reference table C' is utilized to determine the scaling factor of the u-component iu and reference table C is utilized to determine the scaling factor for the v-component iv. The u-component iu is substantially the product of the scaling factor selected from reference table C' and the phase current sense signal IPHW and the v-component iv is substantially the product of the scaling factor selected from reference table C and the phase current sense signal IPHW.

If phase current sense signal IPHU is available for sector <NUM>, reference table B' is utilized to determine the scaling factor for the w-component iw and reference table A' is utilized to determine the scaling factor for the v-component iv. If phase current sense signal IPHV is available for sector <NUM>, reference table A is utilized to determine the scaling factor of the u-component iu and reference table B is utilized to determine the scaling factor for the w-component iw. However, these sections of the <NUM> are grayed out, as generally in sector <NUM>, it is phase current sense signals IPHW which is available.

As such, in response to the stator current angle Θαβ, the sector and the sector angle Θsector may be determined and the appropriate reference table and scaling factor is selected in response to the available phase current sense signals IPHU, IPHV, IPHW to reconstruct the other phase currents magnitudes which are unavailable.

<FIG> illustrates another table <NUM> showing the contents of the reference tables A, B and C for reconstructing the phase currents. As mentioned above, the reference tables utilize the index Θindex to indicate the location of the prestored value in the reference table. In one example, the prestored values are representative of the scaling factors utilized to reconstruct the phase current magnitudes. Further, the prestored values are also computed based on the index Θindex. The index Θindex is substantially the difference between the stator current angles Θαβ and the sector angle Θsector, or mathematically: Θindex = Θαβ - Θsector. As such, the index Θindex has sixty values and varies from <NUM> degrees to fifty-nine degrees (<NUM>°-<NUM>°).

Each of reference tables A, B, and C store values corresponding to different values of the index Θindex. In one example, each of reference tables A, B, and C store values in one-degree increments for sixty degrees of the index Θindex. For reference table A, each stored value representative of the scaling factors is substantially equal to the sine of the sum of the index Θindex and one hundred twenty degrees divided by the sine of the index Θindex, or mathematically: <MAT>.

For reference table B, each stored value representative of the scaling factors is substantially equal to the sine of the difference of the index Θindex and one hundred twenty degrees divided by the sine of the index Θindex, or mathematically: <MAT>.

For reference table C, each stored value representative of the scaling factors is substantially equal to the sine of the index Θindex divided by the sine of the difference of the index Θindex and one hundred twenty degrees, or mathematically: <MAT>.

Reference tables A', B', and C' substantially correspond with reference tables A, B, and C, however, are indexed in reverse from reference tables A, B, and C. For example, a prestored value stored in reference table A at a location corresponding to index Θindex at zero degrees (<NUM>°). The same prestored value is stored in reverse in reference table A'. For example, the prestored value is stored at a location corresponding to index Θindex at fifty-nine degrees (<NUM>°) in reference table A'. A prestored value is stored in reference table A at a location corresponding to index Θindex at one degree (<NUM>°). The same prestored value is stored at a location corresponding to index Θindex at fifty-eight degrees (<NUM>°) in reference table A', and so on and so forth. This indexing is similar for reference table B with reference table B', and reference table C and reference table C'.

As mentioned previously, embodiments of the present disclosure utilize phase current sense signals IPHU, IPHV, IPHW which facilitates the overall reduction of component count, cost, power loss as compared to traditional phase current feedback. In addition, the utilization of reference tables allows for increased processing speeds for phase current reconstruction.

<FIG> illustrates table <NUM> which shows another example process for selecting the reconstruction reference table in response to the stator current angle Θαβ and which one of the phase current sense signal IPHU, IPHV, or IPHW is available. In embodiments of the present disclosure, for each sector there are two phase currents which cross and are substantially opposites of each other while the other phase current has the opposite polarity. For example, in sector <NUM>, phase currents IPHASEU <NUM> and IPHASEW <NUM> are crossing and phase current IPHASEV <NUM> is of the opposite polarity of phase currents IPHASEU <NUM> and IPHASEW <NUM>. In sector <NUM>, phase currents IPHASEV <NUM> and IPHASEW <NUM> are crossing while phase current IPHASEU <NUM> is of the opposite polarity of phase currents IPHASEV <NUM> and IPHASEW <NUM>. So on and so forth. Further, in an "even" sector (sectors <NUM>, <NUM>, and <NUM>), the phase currents which are crossing are negative in polarity and in the "odd" sectors (sectors <NUM>, <NUM>, and <NUM>), the phase currents which are crossing are positive in polarity. As such, another pattern was recognized and the three reference tables utilized with respect to <FIG> could be simplified to two reference tables, referred to as reference table E and reference table D.

As mentioned above, the sector and sector angle Θsector are determined from the stator current angle Θαβ. Once the sector is determined, the appropriate reference table is selected in response to which of the phase current sense signals IPHU, IPHV, IPHW are available. In other words, the phase current reconstructor determines which of the phase current sense signals IPHU, IPHV, and IPHW is greater than its respective threshold UMIN, VMIN, and WMIN.

Referring to the first row corresponding to sector <NUM> for stator current angles Θαβ from ninety to one hundred forty-nine degrees (<NUM>°-<NUM>°). Sector <NUM> is an even number, and as such reference table E and E' are utilized to reconstruct the phase currents. If phase current sense signal IPHU is available for sector <NUM>, reference table E' is utilized to determine the scaling factor for the v-component iv and the v-component iv is substantially the product of the scaling factor from reference table E' and phase current sense signal IPHU. If phase current sense signal IPHW is available for sector <NUM>, reference table E is utilized to determine the scaling factor for the v-component iv and the v-component iv is substantially the product of the scaling factor from reference table E and phase current sense signal IPHW.

<FIG> illustrates the selection of reference table E, E' and reference table D, D'. Reference tables E and D may also be referred to as first reference table (E) and second reference table (D). Reference tables E' and D' substantially correspond with reference tables E and D, respectively, however, are indexed in reverse from reference tables E and D. Reference tables E' and D' may also be referred to as the reverse first reference table (E') and reverse second reference table (D'). As mentioned above, the index Θindex for references tables is substantially the difference between the stator current angles Θαβ and the sector angle Θsector, or mathematically: Θindex = Θαβ - Θsector. As such, in one example, the index Θindex has sixty values and varies from <NUM> degrees to fifty-nine degrees (<NUM>°-<NUM>°).

For example, prestored values representative of scaling factors are stored in reference table E at a location corresponding to index Θindex at zero degrees (<NUM>°). The same prestored value is stored in reverse in reference table E'. For example, the prestored value is stored at a location corresponding to index Θindex at fifty-nine degrees (<NUM>°) in reference table E'. A prestored value is stored in reference table E at a location corresponding to index Θindex at one degree (<NUM>°). The same prestored value is stored at a location corresponding to index Θindex at fifty-eight degrees (<NUM>°) in reference table E', and so on and so forth. This indexing is similar for reference table D and D'.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from one hundred fifty to two hundred nine degrees (<NUM>°-<NUM>°). Sector <NUM> is an odd number, and as such reference table D and D' are utilized to reconstruct the phase currents. If phase current sense signal IPHU is available for sector <NUM>, reference table D is utilized to determine the scaling factor for the w-component iw and reference table D' is utilized to determine the scaling factor for the v-component iv. The w-component iw is substantially the product of the scaling factor from reference table D and the phase current sense signal IPHU. The v-component iv is substantially the product of the scaling factor from reference table D' and the phase current sense signal IPHU.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from two hundred ten to two hundred sixty-nine degrees (<NUM>°-<NUM>°). Sector <NUM> is an even number, and as such reference tables E and E' are utilized. If phase current sense signal IPHU is available for sector <NUM>, reference table E is utilized to determine the scaling factor for the w-component iw. The w-component iw is substantially the product of the scaling factor from reference table E and the phase current sense signal IPHU. If phase current sense signal IPHV is available for sector <NUM>, reference table E' is utilized to determine the scaling factor for the w-component iw. The w-component iw is substantially the product of the scaling factor from reference table E' and the phase current sense signal IPHV.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from two hundred seventy to three hundred twenty-nine (<NUM>°-<NUM>°). Sector <NUM> is an odd number, and as such reference table D and D' are utilized to reconstruct the phase currents. If phase current sense signal IPHV is available for sector <NUM>, reference table D is utilized to determine the scaling factor of the u-component iu and reference table D' is utilized to determine the scaling factor for the w-component iw. The u-component iw is substantially the product of the scaling factor from reference table D and the phase current sense signal IPHV. The v-component iv is substantially the product of the scaling factor from reference table D' and the phase current sense signal IPHV.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from three hundred thirty to three hundred fifty-nine and zero to twenty-nine degrees (<NUM>°-<NUM>°; <NUM>°-<NUM>°). Sector <NUM> is an even number, and as such reference tables E and E' are utilized. If phase current sense signal IPHW is available for sector <NUM>, reference table E' is utilized to determine the scaling factor of the u-component iu. The u-component iu is substantially the product of the scaling factor from reference table E' and the phase current sense signal IPHW. If phase current sense signal IPHV is available for sector <NUM>, reference table E is utilized to determine the scaling factor of the u-component iv. The u-component iu is substantially the product of the scaling factor from reference table E and the phase current sense signal IPHV.

Referring to row <NUM> of table <NUM> corresponding to sector <NUM> for stator current angles Θαβ from thirty to eighty-nine degrees (<NUM>°-<NUM>°). Sector <NUM> is an odd number, and as such reference table D and D' are utilized to reconstruct the phase currents. If phase current sense signal IPHW is available for sector <NUM>, reference table D' is utilized to determine the scaling factor of the u-component iu and reference table D is utilized to determine the scaling factor for the v-component iv. The w-component iw is substantially the product of the scaling factor from reference table D' and the phase current sense signal IPHW. The v-component iv is substantially the product of the scaling factor from reference table D and the phase current sense signal IPHW.

As such, in response to the stator current angle Θαβ, the sector and sector angle Θsector may be determined and the appropriate reference table and scaling factor is selected in response to which of the phase current sense signals IPHU, IPHV, IPHW are available to reconstruct the other phase currents which are unavailable.

<FIG> illustrates another table <NUM> showing the contents of the reference tables D and E for reconstructing the phase currents. As mentioned above, the reference tables utilize the index Θindex to indicate the location of the prestored value in the reference table. Further, the prestored values representative of scaling factors utilized to reconstruct the phase current magnitudes are also computed based on the index Θindex. The index Θindex is substantially the difference between the stator current angles Θαβ and the sector angle Θsector, or mathematically: Θindex = Θαβ - Θsector. As such, in one example, the index Θindex has sixty values and varies from <NUM> degrees to fifty-nine degrees (<NUM>°-<NUM>°).

Each of the reference tables E and D have sixty values stored, each stored value corresponding with one of the sixty values of the index Θindex. For table E, each stored value representative of the scaling factors is substantially equal to the sine of the sum of the index Θindex and sixty degrees divided by the sine of the difference between sixty degrees and index Θindex, or mathematically: <MAT>.

For reference table D, each stored value representative of the scaling factors is substantially equal to the sine of the index Θindex divided by the sine of the sum of the index Θindex and sixty degrees, or mathematically: <MAT>.

Claim 1:
A system controller for a motor drive system, comprising:
a phase current reconstructor (<NUM>) configured to perform operations comprising
receiving an estimate of a stator current angle (<NUM>, <NUM>) and a plurality of phase current sense signals (<NUM>, <NUM>, <NUM>) from a plurality of respective switching devices that in operation drive the motor drive system, the phase current sense signals (<NUM>, <NUM>, <NUM>) being representative of a portion of respective motor phase currents (<NUM>, <NUM>, <NUM>),
selecting, based on the received stator current angle, a reference table (<NUM>) from among a plurality of reference tables that store reconstruction scaling factors for respective phase currents,
obtaining, from the selected reference table, respective reconstruction scaling factors for the respective phase currents,
generating, from the obtained reconstruction scaling factors, respective reconstructed phase current magnitude values (<NUM>, <NUM>, <NUM>) for the plurality of devices, and
outputting the reconstructed phase current magnitude values;
a reference frame translator (<NUM>) configured to receive the output reconstructed phase current magnitude values and to generate an alpha component (<NUM>, <NUM>) and a beta component (<NUM>, <NUM>) of a reference frame of the stator;
a stator current angle estimator (<NUM>) configured to receive the alpha component (<NUM>, <NUM>) and the beta component (<NUM>, <NUM>), to compute the estimate of the stator current angle from the alpha component and the beta component, and to provide the estimate (<NUM>, <NUM>) of the stator current angle back to the phase current reconstructor; and
a control signal generator (<NUM>) configured to generate control signals (<NUM>, <NUM>, <NUM>) for the plurality of switching devices based on the reconstructed phase current magnitude values.