Inverter phase switch with high and low side mosfet resistance diversity

Abstract

Disclosed herein are phase switches for inverters with high-side and low-side MOSFET resistance diversity. One or more embodiments are provided for an inverter. The inverter includes a phase switch configured to supply AC power via an output terminal. The phase switch includes a high-side leg and a low-side leg. The high-side leg includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and the output terminal, and the low-side leg includes a low-side solid-state switch configured to selectively conduct current between the output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first on-state resistance value, and the low-side solid-state switch has a second on-state resistance value different from the first on-state resistance value. A shunt resistor can be connected in series with a corresponding solid-state switch of the high-side solid-state switch or the low-side solid-state switch to balance the resistance of the high-side leg and the low-side leg.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 147,361, filed February 9, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a motor driver for converting direct current (DC) power to alternating current (AC) power. More specifically, this disclosure relates to an inverter used in such a motor driver circuit. Background Technology

[0004] Electric motor drives (also known as variable frequency drives (VFDs)) are used in a variety of applications to provide alternating current (AC) power to electric motors. Electric motor drives are frequently used in electric vehicles to power traction motors at different speed ranges. They also have industrial and commercial applications, such as operating blowers, conveyors, and / or other machines at varying speeds.

[0005] Electric motor drivers may include one or more solid-state switches (e.g., metal-oxide-semiconductor field-effect transistors (MOSFETs)) to switch a DC source to generate AC power. In typical inverters, solid-state switches often have similar types and / or include the same characteristics. Summary of the Invention

[0006] This disclosure generally relates to motor drivers. More specifically, this disclosure relates to the arrangement of solid-state switches in the phase switches of an inverter within a motor driver.

[0007] One aspect of the disclosed embodiments includes an inverter. The inverter includes a phase switch configured to supply AC power via an output terminal. The phase switch includes a high-side leg and a low-side leg. The high-side leg includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of the DC bus and the output terminal. The low-side leg includes a low-side solid-state switch configured to selectively conduct current between the output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first conducting-state resistance value, and the low-side solid-state switch has a second conducting-state resistance value different from the first conducting-state resistance value.

[0008] One aspect of the disclosed embodiments includes a motor driver. The motor driver includes an inverter comprising a plurality of phase switches. Each phase switch is configured to supply AC power to an electric motor via a corresponding output terminal. Each phase switch includes a high-side branch and a low-side branch. The high-side branch includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and a corresponding output terminal. The low-side branch includes a low-side solid-state switch configured to selectively conduct current between a corresponding output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first on-state resistance value, and the low-side solid-state switch has a second on-state resistance value different from the first on-state resistance value.

[0009] These and other aspects of this disclosure are disclosed in the following detailed description of the embodiments, the appended claims and the accompanying drawings. Attached Figure Description

[0010] This disclosure is best understood by reading in conjunction with the accompanying drawings and through the following detailed description. It should be emphasized that, by convention, the various features in the drawings are not drawn to scale. Instead, for clarity, the dimensions of the various features have been arbitrarily enlarged or reduced.

[0011] Figure 1 The vehicle based on the principles of this disclosure is shown in general.

[0012] Figure 2 A schematic diagram of a motor driver based on the principles of this disclosure is shown in general.

[0013] Figure 3 A schematic diagram of a phase switch based on the principles of this disclosure is shown in general. Detailed Implementation

[0014] The following discussion pertains to various embodiments of this disclosure. While one or more of these embodiments may be preferred, the disclosed embodiments should not be construed as or otherwise used to limit the scope of this disclosure, including the claims. Furthermore, those skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is intended only as an exemplary discussion of that embodiment and is not intended to imply that the scope of this disclosure, including the claims, is limited to that embodiment.

[0015] As previously mentioned, vehicles such as cars, trucks, SUVs, crossovers, minivans, speedboats, aircraft, all-terrain vehicles, recreational vehicles, or other suitable vehicles typically include one or more motors, such as electric motors. For example, a vehicle may include one or more multiphase motors configured to control various aspects of the vehicle's steering system.

[0016] Figure 1Vehicle 10, generally illustrated according to the principles of this disclosure, is shown. Vehicle 10 may include any suitable vehicle, such as a car, truck, SUV, minivan, crossover, any other passenger vehicle, any suitable commercial vehicle, or any other suitable vehicle. Although vehicle 10 is illustrated as a passenger vehicle with wheels and used on a road, the principles of this disclosure can be applied to other means of transportation, such as airplanes, ships, trains, drones, or other suitable vehicles.

[0017] Vehicle 10 includes a body 12 and an engine hood 14. A passenger compartment 18 is defined at least partially by the body 12. Another portion of the body 12 defines an engine compartment 20. The engine hood 14 is movably attached to a portion of the body 12 such that when the engine hood 14 is in a first position or open position, the engine hood 14 provides access to the engine compartment 20, and when the engine hood 14 is in a second position or closed position, the engine hood 14 covers the engine compartment 20. In some embodiments, the engine compartment 20 may be located in the rear portion of the vehicle 10 (compared to what is typically shown).

[0018] The passenger compartment 18 may be located behind the engine compartment 20, but in embodiments where the engine compartment 20 is located in the rear portion of the vehicle 10, the passenger compartment 18 may be located in front of the engine compartment 20. The vehicle 10 may include any suitable propulsion system, including an internal combustion engine, one or more electric motors (e.g., an electric vehicle), one or more fuel cells, a hybrid (e.g., a hybrid vehicle) propulsion system including a combination of an internal combustion engine and one or more electric motors, and / or any other suitable propulsion system.

[0019] In some embodiments, vehicle 10 may include a gasoline-powered engine, such as a spark-ignition engine. In some embodiments, vehicle 10 may include a diesel-powered engine, such as a compression-ignition engine. Engine compartment 20 houses and / or surrounds at least some components of the propulsion system of vehicle 10. Additionally or optionally, propulsion control devices (e.g., accelerator actuators, brake actuators, steering wheel, and other such components) are arranged in passenger compartment 18 of vehicle 10. The propulsion control devices may be actuated or controlled by the driver of vehicle 10 and may be directly connected to corresponding components of the propulsion system, such as accelerator, brakes, axles, and vehicle transmission. In some embodiments, the propulsion control devices may transmit signals to a vehicle computer (e.g., drive-by-wire), which in turn may control the corresponding propulsion components of the propulsion system. Thus, in some embodiments, vehicle 10 may be an autonomous vehicle.

[0020] In some embodiments, vehicle 10 includes a transmission that communicates with the crankshaft via a flywheel, clutch, or hydraulic coupling. In some embodiments, the transmission includes a manual transmission. In some embodiments, the transmission includes an automatic transmission. In the case of an internal combustion engine or hybrid vehicle, vehicle 10 may include one or more pistons that cooperate with the crankshaft to generate force, which is transmitted through the transmission to one or more shafts to rotate wheels 22. When vehicle 10 includes one or more electric motors, a vehicle battery and / or fuel cell provides energy to the electric motors to rotate wheels 22.

[0021] Vehicle 10 may include an autonomous vehicle propulsion system, such as cruise control, adaptive cruise control, automatic braking control, other autonomous vehicle propulsion systems, or combinations thereof. Vehicle 10 may be an autonomous vehicle or a semi-autonomous vehicle, or other suitable type of vehicle. Vehicle 10 may include additional or fewer features compared to those generally shown and / or disclosed herein.

[0022] In some embodiments, vehicle 10 may include an Ethernet component 24, a controller area network (CAN) bus 26, a media-oriented system transport component (MOST) 28, a FlexRay component 30 (e.g., a brake-by-wire system), and a local interconnect network component (LIN) 32. Vehicle 10 may use the CAN bus 26, MOST 28, FlexRay component 30, LIN 32, other suitable network or communication systems, or combinations thereof, to transmit various information from, for example, sensors inside or outside the vehicle, to, for example, various processors or controllers inside or outside the vehicle. Vehicle 10 may include additional or fewer features compared to those generally shown and / or disclosed herein.

[0023] Many conventional motor control strategies used to control AC motors (e.g., three-phase brushless motors) involve precisely monitoring and controlling the current in each phase. To generate this current, inverters use solid-state switches (e.g., metal-oxide-semiconductor field-effect transistors (MOSFETs)) to attempt to produce a specific voltage waveform across the motor's terminals.

[0024] Figure 2 A schematic diagram of a motor driver 110 according to the principles of this disclosure is shown. The motor driver 110 is a three-phase driver configured to supply AC current to a three-phase motor 112. The three-phase motor 112 may be a brushless permanent magnet motor (e.g., a permanent magnet synchronous motor (PMSM)), although it may be another type of motor or motor / generator, such as an induction motor or a wound field machine. The three-phase motor 112 is shown having three motor windings 114, also referred to as phases. A ,Mutually B ,Mutually CThey are connected in a Y-shaped configuration with a common central node. The three-phase motor 112 can have any number of windings, which can be connected in other configurations, such as a delta configuration.

[0025] The motor driver 110 includes a battery serving as a direct current (DC) source 120 to supply DC power on DC buses 122a, 122b, which include a high-side conductor 122a and a low-side conductor 122b, wherein the high-side conductor 122a has a higher voltage potential than the low-side conductor 122b. The motor driver 110 also includes an inverter 126 with three phase switches 128a, 128b, 128c, each phase switch 128a, 128b, 128c configured to switch current from the DC buses 122a, 122b to supply AC power at corresponding output terminals 129a, 129b, 129c. Output terminals 129a, 129b, 129c are connected to corresponding output terminals of three output terminals 130, which deliver AC power as three-phase AC power to the three-phase motor 112. It should be understood that the motor driver 110 may include a different number of phases, such as a single phase or more than three phases. For example, the motor driver 110 may include five or more phase switches 128a, 128b, 128c, each phase switch being configured to switch current from DC bus 122a, 122b to supply AC power on a corresponding one of five or more output terminals 129a, 129b, 129c.

[0026] Each of the phase switches 128a, 128b, and 128c within the inverter 126 of the motor driver 110 includes a high-side solid-state switch 134 configured to selectively conduct current between a corresponding output terminal of the output terminals 129a, 129b, and 129c and the high-side conductor 122a of the DC buses 122a and 122b. Each of the phase switches 128a, 128b, and 128c also includes a low-side solid-state switch 136 configured to selectively conduct current between a corresponding output terminal of the output terminals 129a, 129b, and 129c and the low-side conductor 122b of the DC buses 122a and 122b.

[0027] Pulse width modulation (PWM) waveforms are used to sequentially activate the solid-state switches 134, 136 that generate the desired current waveform in the motor winding 114. The current waveform in the motor winding 114 is a byproduct of the voltage waveform generated by the solid-state switches 134, 136 of the inverter 126. In a circuit, one of the key parameters determining the current is the circuit resistance. In a steady-state circuit, the current can be determined by the following equation (1), where V is the voltage across the circuit, R is the circuit resistance, and I is the current in the circuit.

[0028] V=I*R (1)

[0029] In a given circuit, the sum of the currents through any node must be zero. In the case of a Y-wound motor, each phase is connected at the neutral node, so the sum of the currents in each phase must be zero. If the motor circuit is simplified to include only resistive components, equation (1) can be combined with this information to derive equation (2).

[0030]

[0031] In equation (2), V A V B and V C Each value in the table represents the voltage of the corresponding output terminals 129a, 129b, and 129c relative to ground. These subscripts indicate specific phases. Variable R A R B R C Each of these parameters defines the corresponding resistance from each output terminal 129a, 129b, 129c to the neutral node. Variable I A This indicates the current flowing through phase A, or the current supplied from phase A output terminal 129a to the phase A winding of motor 112. A The current in each phase depends on the resistance of that phase and the voltage applied to that phase. Based on this equation, it is clear that the current in each phase depends on the resistance of that phase and the voltage applied to that phase.

[0032] The path between the high-side conductor 122a of DC buses 122a and 122b and each of the output terminals 129a, 129b, and 129c can be referred to as the high-side branch of the corresponding phase switch in phase switches 128a, 128b, and 128c. The path between the low-side conductor 122b of DC buses 122a and 122b and each of the output terminals 129a, 129b, and 129c can be referred to as the low-side branch of the corresponding phase switch in phase switches 128a, 128b, and 128c.

[0033] To ensure that the current waveform generated by inverter 126 is as desired, the current flowing through each low-side branch is determined by measuring the voltage across a shunt resistor 138 connected in series with the low-side solid-state switch 136 in each of the phase switches 128a, 128b, and 128c. This measurement using shunt 126 is performed using equation (1), and I is solved using a known R and a measured V. This measurement can be used as feedback for closed-loop control of the motor current supplied to motor 112. Placing the shunt resistor 138 in the low-side branches of phase switches 128a, 128b, and 128c adds resistance to the low-side branches because this resistance is required to generate a voltage across the shunt resistor 138. This additional resistance means that the low-side branches of phase switches 128a, 128b, and 128c will have a higher resistance if all other components are balanced in terms of resistance. The voltage applied to each phase is determined by the duty cycle of the high-side solid-state switch 134 and the low-side solid-state switch 136. The percentage of time the high-side solid-state switch 134 is on determines the percentage of DC positive voltage applied to the corresponding output terminals 129a, 129b, and 129c. This percentage is then subtracted from 1 to determine the percentage of time the low-side solid-state switch 136 is on. Therefore, the resistance contribution of the high-side and low-side inverter branches is based on the percentage of time each solid-state switch 134, 136 is on, and the resistance in each corresponding section of the phase switches 128a, 128b, and 128c. Because this changing voltage alters the proportion of time the high-side solid-state switch 134 and the low-side solid-state switch 136 are on, this also changes the resistance in the entire phase switches 128a, 128b, and 128c. This changing resistance acts like a forcing function on the closed-loop current control and affects the response of the control system, as the current regulator must now change the applied voltage to achieve the same current.

[0034] Figure 3 It shows Figure 2 An enlarged portion of the schematic diagram of the motor driver 110 shows the phase switch 128a of phase A.

[0035] The inverter circuit can be balanced with the shunt resistor 138 in the low-side branch by carefully selecting the components used to implement the high-side solid-state switch 134 and the low-side solid-state switch 136. These components can include, for example, different types of MOSFETs. To best balance the inverter branch, the device selected for the low-side solid-state switch 136 can have a resistance equal to the resistance of the high-side solid-state switch 134 minus the resistance of the shunt resistor 138, as shown in equation (3) below. In equation (3), the resistance of each component is represented by R with a subscript describing the component. In this equation, R Low It is the resistor R of the low-side solid-state switch 136. HighIt is the resistor of the high-side solid-state switch 134, and R Shunt It is a shunt resistor 138 used for low-side current measurement.

[0036] R Low =R High -R Shunt (3)

[0037] For example, Figure 3 The high-side solid-state switch 134 of the phase switch 128a shown may have a nominal on-state resistance of 1.9 mΩ (milliohms). The low-side branch of the phase switch 128a includes a series combination of a low-side solid-state switch 136 and a shunt resistor 138. The low-side solid-state switch 136 may have a nominal on-state resistance of 1.4 mΩ (milliohms), and the shunt resistor 138 may have a nominal resistance of 0.5 mΩ (milliohms). When the low-side solid-state switch 136 is in the on state, the series combination of the low-side solid-state switch 136 and the shunt resistor 138 has a combined nominal resistance of 1.9 mΩ (milliohms). This provides equivalent or balanced nominal resistances for the high-side and low-side branches. The actual resistances of the high-side solid-state switch 134, the low-side solid-state switch 136, and / or the shunt resistor 138 may vary slightly from their respective nominal resistance values. For each of the high-side solid-state switch 134, the low-side solid-state switch 136, and / or the shunt resistor 138, the amount of deviation between the actual resistance and the nominal resistance can be specified within a given tolerance.

[0038] The high-side solid-state switch 134 and the low-side solid-state switch 136 may have on-state resistances determined at least in part based on the nominal voltage of the DC source 120. The shunt resistor 138 may also have a resistance value determined at least in part based on the nominal voltage of the DC source 120. For example, in the case where the DC source 120 has a nominal voltage of twelve (12) volts, the high-side solid-state switch 134 and the low-side solid-state switch 136 may each have a nominal on-state resistance value of less than 2.0 milliohms. In another configuration where the DC source 120 has a nominal voltage of forty-eight (48) volts, the high-side solid-state switch 134 and the low-side solid-state switch 136 may each have a nominal on-state resistance value of 4 to 8 milliohms, and the shunt resistor 138 may have a resistance value of 1 to 3 milliohms.

[0039] This technique can also be extended to compensate for conductor resistance. Conductors in the circuit (e.g., traces on components connected to the circuit board of inverter 126) may also add additional resistance. In this case, equation (3) can be extended to equation (4) below.

[0040] R L_FET =R H_FET +R H_Trace –RL_Trace –R Shunt (4)

[0041] In equation (4), the solid-state switching components are now represented by the subscripts “L_FET” and “H_FET” of the low-side solid-state switch 136 and the high-side solid-state switch 134, respectively. The variables “H_Trace” and “L_Trace” are added to represent the high-side trace and the low-side trace, respectively. The resistance of the shunt resistor 138 used for low-side current measurement is given by R. Shunt Equation (3) is the same. Equation (4) illustrates how the solid-state switch assembly can be selected in a way that balances the low-side and high-side branches and reduces the forced function imbalance introduced into the motor control system used to control the operation of solid-state switches 134 and 136.

[0042] In one example embodiment, the high-side solid-state switch 134 has a nominal on-state resistance of 1.9 mΩ, the low-side solid-state switch 136 has a nominal on-state resistance of 1.4 mΩ, and the shunt resistor 138 has a resistance of 0.5 mΩ. In another example embodiment, the high-side solid-state switch 134 has a nominal on-state resistance of 1.0 mΩ, and the low-side solid-state switch 136 has a nominal on-state resistance of 0.64 mΩ and is connected in series with the shunt resistor 138. In yet another example embodiment, the high-side solid-state switch 134 has a nominal on-state resistance of 1.2 mΩ, and the low-side solid-state switch 136 has a nominal on-state resistance of 1.0 mΩ and is connected in series with the shunt resistor 138.

[0043] In some embodiments, the high-side solid-state switch 134 and the low-side solid-state switch 136 may each have different physical packages. For example, the high-side solid-state switch 134 may include a 5mm × 6mm package, and the low-side solid-state switch 136 may include a 7mm × 8mm package. Either or both of the high-side solid-state switch 134 and / or the low-side solid-state switch 136 may include surface-mount packages, such as packages conforming to the JEDEC Solid State Technology Association standard MO-319A. In some embodiments, either or both of the high-side solid-state switch 134 and / or the low-side solid-state switch 136 may include leadless packages, such as Infineon's sTOLL type package.

[0044] Alternatively, the shunt resistor 138 may be connected in series with the high-side solid-state switch 134. However, this arrangement may require different sensing hardware to measure the current through the shunt resistor 138.

[0045] Typically, solid-state switching components in motor drives 110 used in vehicle applications, such as those in electric power steering (EPS) systems, are selected with the same part number. This design, combined with shunts 138 for current measurement, naturally leads to an imbalance in inverter branch resistance. The phase switches of this disclosure correct this imbalance by intentionally selecting two different component types for the high-side solid-state switch 134 and the low-side solid-state switch 136, wherein these two different component types have different on-state resistance values. The on-state resistance value can each represent the resistance through the current-carrying path when the corresponding solid-state switch in solid-state switches 134, 136 is in the on-state. For example, for solid-state switches including field-effect transistors (FETs), the on-state resistance can represent the drain-source resistance of the FET when it is in the on-state. The on-state can also be referred to as the "ON" state. The drain-source resistance of this ON state can be denoted as r. ds_on The two different component types used for the high-side solid-state switch 134 and the low-side solid-state switch 136 can each be the same general-purpose MOSFET. However, different device types can be used. For example, one of the high-side solid-state switch 134 or the low-side solid-state switch 136 can be a specific type of MOSFET, while the other of the high-side solid-state switch 134 or the low-side solid-state switch 136 can be a different type of field-effect transistor (FET) or a different type of semiconductor device, such as a junction transistor. The on-state resistance value can be the resistance across the conductive path when the solid-state switch is in the on state, such as the drain-source resistance.

[0046] The configuration of the high-side solid-state switch 134 and the low-side solid-state switch 136 with different on-state resistances can improve the unique problem of low-side current measurement by balancing the high-side and low-side branches. This configuration of different on-state resistances in the high-side solid-state switch 134 and the low-side solid-state switch 136 can also improve the response of the current regulator by eliminating the forced function from the controlled system. This diversity of components can also provide reduced system cost and improved thermal performance.

[0047] Typically, as the resistance of a solid-state switch decreases, its cost increases while its heat dissipation decreases. This inverse relationship means that if the system requires high current, the cost of the solid-state switch increases. However, in some motor control strategies, not all solid-state switches 134, 136 receive the same amount of current. In these cases, it is generally true that the lower-side solid-state switch 136 spends more time in the ON state. The balancing strategy of this disclosure allows the cost to be added only to the solid-state switch most affected. This strategy also allows the inverter 126 to combine solid-state switches 134, 136 with different price points while maintaining the current-carrying capacity of the system.

[0048] The phase switches 128a, 128b, and 128c of this disclosure (including a high-side solid-state switch 134 and a low-side solid-state switch 136 with different on-state resistance values) can be used in many different applications. For example, phase switches 128a, 128b, and 128c can be used in motor drives or other inverter applications. The phase switches 128a, 128b, and 128c of this disclosure can be used in motor drives of various systems within vehicle 10. For example, phase switches 128a, 128b, and 128c of this disclosure can be used in steering systems of vehicle 10, such as electric power steering (EPS) systems, advanced driver assistance system (ADAS) controlled steering, or steer-by-wire (SbW) systems. The phase switches 128a, 128b, and 128c of this disclosure may or may not include an in-line current measurement system (i.e., shunt 138).

[0049] The phase switches 128a, 128b, and 128c of this disclosure (including a high-side solid-state switch 134 and a low-side solid-state switch 136 with different on-state resistance values) can provide several advantages over conventional designs. These advantages may include: 1. improved control characteristics and minimization of generated torque ripple; 2. improved system thermal management capabilities by allowing the lower resistance of the solid-state switch on the low side to operate in the on-state for a longer period of time; 3. "In-ECU" hardware diversity for process-related fault management avoidance; and / or 4. greater cost optimization based on component selection of solid-state switches 134 and 136.

[0050] This disclosure provides an inverter including a phase switch configured to supply AC power via an output terminal. The phase switch includes a high-side branch and a low-side branch. The high-side branch includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and the output terminal. The low-side branch includes a low-side solid-state switch configured to selectively conduct current between the output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first on-state resistance value, and the low-side solid-state switch has a second on-state resistance value different from the first on-state resistance value.

[0051] In some embodiments, at least one of the high-side branch or the low-side branch further includes a shunt resistor connected in series with the corresponding solid-state switch in the high-side solid-state switch or the low-side solid-state switch.

[0052] In some embodiments, the series combination of the shunt resistor and a corresponding solid-state switch of the high-side solid-state switch or the low-side solid-state switch has a combined series resistance approximately equal to the on-state resistance value of the other solid-state switch of the high-side solid-state switch or the low-side solid-state switch, in order to balance the resistance of the high-side branch and the resistance of the low-side branch.

[0053] In some embodiments, the series combination of the shunt resistor and a corresponding solid-state switch of the high-side solid-state switch or the low-side solid-state switch has a combined nominal series resistance approximately equal to the nominal value of the on-state resistance of the other solid-state switch of the high-side solid-state switch or the low-side solid-state switch, in order to balance the nominal resistance of the high-side branch and the nominal resistance of the low-side branch.

[0054] In some embodiments, the shunt resistor is connected in series with the low-side solid-state switch.

[0055] In some embodiments, the shunt resistor is connected in series with the high-side solid-state switch.

[0056] In some embodiments, the high-side solid-state switch and the low-side solid-state switch each have different physical package types.

[0057] In some embodiments, the high-side solid-state switch and the low-side solid-state switch each have a nominal on-state resistance of less than 8.0 milliohms.

[0058] In some embodiments, the high-side solid-state switch and the low-side solid-state switch each have a nominal on-state resistance value of less than or equal to 2.0 milliohms.

[0059] In some embodiments, the high-side solid-state switch has a nominal on-state resistance of 1.0 milliohms, and the low-side solid-state switch has a nominal on-state resistance of 0.64 milliohms.

[0060] In some embodiments, the high-side solid-state switch has a nominal on-state resistance of 1.2 milliohms, and the low-side solid-state switch has a nominal on-state resistance of 1.0 milliohms.

[0061] In some embodiments, the high-side solid-state switch has a nominal on-state resistance of 1.9 milliohms, the low-side solid-state switch has a nominal on-state resistance of 1.4 milliohms, and the shunt resistor has a nominal resistance of 0.5 milliohms.

[0062] In some embodiments, a phase switch is one of a plurality of phase switches, and each phase switch is configured to supply AC power via a corresponding output terminal.

[0063] This disclosure provides a motor driver including an inverter comprising a plurality of phase switches, each phase switch configured to supply AC power to an electric motor via a corresponding output terminal. Each phase switch includes a high-side branch and a low-side branch. The high-side branch includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and a corresponding output terminal. The low-side branch includes a low-side solid-state switch configured to selectively conduct current between a corresponding output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first on-state resistance value, and the low-side solid-state switch has a second on-state resistance value different from the first on-state resistance value.

[0064] In some embodiments, the plurality of phase switches includes at least three phase switches.

[0065] In some embodiments, the low-side branch further includes a shunt resistor connected in series with the low-side solid-state switch.

[0066] In some embodiments, at least one of the high-side branch or the low-side branch further includes a shunt resistor connected in series with a corresponding solid-state switch in the high-side or low-side solid-state switch, and the series combination of the shunt resistor and the corresponding solid-state switch in the high-side or low-side solid-state switch has a nominal value equal to the on-state resistance of the other solid-state switch in the high-side or low-side solid-state switch, so as to balance the nominal resistance of the high-side branch and the nominal resistance of the low-side branch.

[0067] In some embodiments, the high-side solid-state switch and the low-side solid-state switch each have different physical package types.

[0068] In some embodiments, the high-side solid-state switch and the low-side solid-state switch each have a nominal on-state resistance of less than 2.0 milliohms.

[0069] In some embodiments, the electric power steering system includes the motor driver disclosed herein.

[0070] The foregoing discussion is intended to illustrate the principles and various embodiments of this disclosure. Once the foregoing disclosure is fully understood, many variations and modifications will become apparent to those skilled in the art. The following claims are intended to be construed as encompassing all such variations and modifications.

[0071] The word “example” is used herein to mean something used as an example, illustration, or description. Any aspect or design described herein as an “example” is not necessarily to be construed as being more preferred or advantageous than other aspects or designs. Rather, the use of the word “example” is intended to present a concept in a specific manner. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise stated or clearly apparent from the context, “X comprises A or B” is intended to mean any natural inclusion. That is, if X comprises A; X comprises B; or X comprises both A and B, then “X comprises A or B” is satisfied in any of the foregoing cases. Additionally, the article “a / an” used in this application and the appended claims should generally be interpreted as meaning “one or more” unless otherwise stated or clearly apparent from the context to the singular form. Furthermore, unless so described, the use of the terms “an embodiment” or “one embodiment” throughout the document is not intended to refer to the same embodiment or implementation.

[0072] The embodiments, implementations, and aspects described above are intended to facilitate an easy understanding of this disclosure and do not limit the invention. Rather, this disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which should be given the broadest interpretation to cover all such modifications and equivalent structures permitted by law.

Claims

1. An inverter, comprising: A phase switch configured to supply AC power via an output terminal includes a high-side branch and a low-side branch. The high-side branch includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and the output terminal, and the low-side branch includes a low-side solid-state switch configured to selectively conduct current between the output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first on-state resistance value, and the low-side solid-state switch has a second on-state resistance value that is different from the first on-state resistance value. At least one of the high-side branch or the low-side branch further includes a shunt resistor, which is connected in series with a corresponding solid-state switch in the high-side solid-state switch or the low-side solid-state switch. The shunt resistor, in series with a corresponding solid-state switch of the high-side solid-state switch or the low-side solid-state switch, has a combined series resistance equal to the on-state resistance value of the other solid-state switch of the high-side solid-state switch or the low-side solid-state switch, in order to balance the resistance of the high-side branch and the resistance of the low-side branch.

2. The inverter according to claim 1, wherein, The shunt resistor is connected in series with the low-side solid-state switch.

3. The inverter according to claim 1, wherein, The shunt resistor is connected in series with the high-side solid-state switch.

4. The inverter according to claim 1, wherein, The high-side solid-state switch and the low-side solid-state switch each have different physical package types.

5. The inverter according to claim 1, wherein, The high-side solid-state switch and the low-side solid-state switch each have a nominal on-state resistance of less than 8.0 milliohms.

6. The inverter according to claim 1, wherein, The high-side solid-state switch and the low-side solid-state switch each have a nominal on-state resistance value of less than or equal to 2.0 milliohms.

7. The inverter according to claim 1, wherein, The high-side solid-state switch has a nominal on-state resistance of 1.0 milliohms, and the low-side solid-state switch has a nominal on-state resistance of 0.64 milliohms.

8. The inverter according to claim 1, wherein, The high-side solid-state switch has a nominal on-state resistance of 1.2 milliohms, and the low-side solid-state switch has a nominal on-state resistance of 1.0 milliohms.

9. The inverter according to claim 1, wherein, The high-side solid-state switch has a nominal on-state resistance of 1.9 milliohms, the low-side solid-state switch has a nominal on-state resistance of 1.4 milliohms, and the shunt resistor has a nominal resistance of 0.5 milliohms.

10. The inverter according to claim 1, wherein, The phase switch is one of a plurality of phase switches, and each phase switch is configured to supply AC power via a corresponding output terminal.

11. An inverter, comprising: A phase switch configured to supply AC power via an output terminal includes a high-side branch and a low-side branch. The high-side branch includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and the output terminal, and the low-side branch includes a low-side solid-state switch configured to selectively conduct current between the output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first on-state resistance value, and the low-side solid-state switch has a second on-state resistance value that is different from the first on-state resistance value. At least one of the high-side branch or the low-side branch further includes a shunt resistor, which is connected in series with a corresponding solid-state switch in the high-side solid-state switch or the low-side solid-state switch. The shunt resistor, in series with a corresponding solid-state switch of the high-side solid-state switch or the low-side solid-state switch, has a combined nominal series resistance equal to the nominal value of the on-state resistance of the other solid-state switch of the high-side solid-state switch or the low-side solid-state switch, in order to balance the nominal resistance of the high-side branch and the nominal resistance of the low-side branch.

12. A motor driver, comprising: An inverter includes multiple phase switches, each configured to supply AC power to an electric motor via a corresponding output terminal. Each phase switch includes a high-side branch and a low-side branch. The high-side branch includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and the corresponding output terminal. The low-side branch includes a low-side solid-state switch configured to selectively conduct current between the corresponding output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first on-state resistance value, and the low-side solid-state switch has a second on-state resistance value that is different from the first on-state resistance value. At least one of the high-side branch or the low-side branch further includes a shunt resistor, which is connected in series with a corresponding solid-state switch in the high-side solid-state switch or the low-side solid-state switch. The shunt resistor, in series with a corresponding solid-state switch of the high-side solid-state switch or the low-side solid-state switch, has a combined series resistance equal to the on-state resistance value of the other solid-state switch of the high-side solid-state switch or the low-side solid-state switch, in order to balance the resistance of the high-side branch and the resistance of the low-side branch.

13. The motor driver according to claim 12, wherein, The plurality of phase switches includes at least three phase switches.

14. The motor driver according to claim 12, wherein, The low-side branch also includes a shunt resistor connected in series with the low-side solid-state switch.

15. The motor driver according to claim 12, wherein, The high-side solid-state switch and the low-side solid-state switch each have different physical package types.

16. The motor driver according to claim 12, wherein, The high-side solid-state switch and the low-side solid-state switch each have a nominal on-state resistance value of less than 2.0 milliohms.

17. A motor drive, comprising: An inverter includes multiple phase switches, each configured to supply AC power to an electric motor via a corresponding output terminal. Each phase switch includes a high-side branch and a low-side branch. The high-side branch includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and the corresponding output terminal. The low-side branch includes a low-side solid-state switch configured to selectively conduct current between the corresponding output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first on-state resistance value, and the low-side solid-state switch has a second on-state resistance value that is different from the first on-state resistance value. At least one of the high-side branch or the low-side branch further includes a shunt resistor connected in series with the corresponding solid-state switch in the high-side or low-side solid-state switch, and The shunt resistor, in series with a corresponding solid-state switch of the high-side solid-state switch or the low-side solid-state switch, has a combined nominal series resistance equal to the nominal value of the on-state resistance of the other solid-state switch of the high-side solid-state switch or the low-side solid-state switch, in order to balance the nominal resistance of the high-side branch and the nominal resistance of the low-side branch.

18. An electric power steering system, comprising a motor driver according to claim 12 or 17.

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