RESISTORLESS MOTOR CONTROL

Abstract

A controller operates a bridge circuit in a freewheeling phase, during which a freewheeling current flows through a body diode of a power transistor in the bridge circuit. The controller performs a first measurement during the freewheeling phase to determine the junction temperature of the power transistor. The controller performs a second measurement during the freewheeling phase to determine the drain voltage of the power transistor.

Description

TECHNICAL AREA OF INVENTION

[0001] This disclosure relates to motor control and, in particular, techniques for measuring current through a motor without the use of a measuring resistor. BACKGROUND

[0002] Power transistors are used in a wide variety of applications to control the power delivered to a load, such as a motor. Examples of power transistors include field-effect transistors (FETs), insulated-gate bipolar transistors (IGBTs), bipolar junction transistors (BJTs), and other types of power transistors. Examples of FETs include, but are not limited to, junction field-effect transistors (JFETs), metal-oxide-semiconductor FETs (MOSFETs), dual-gate MOSFETs, insulated-gate bipolar transistors (IGBTs), any other type of FET, or any combination thereof. Examples of MOSFETs include, but are not limited to, PMOS, NMOS, DMOS, or any other type of MOSFET, or any combination thereof. MOSFETs can be made of silicon, gallium nitride, silicon carbide, or other materials.

[0003] Power transistors are typically controlled by a driver circuit via pulse modulation (PM) signals. PM signals generally refer to pulse width modulation (PWM), pulse frequency modulation (PFM), pulse duration modulation, pulse density modulation, or some other type of modulated control signal used to control a power switch. PM control signals can be generated by a processor and communicated to a driver circuit. The driver circuit can amplify the PM control signals to create PM driver signals that can be applied to the gate of a power transistor to control the switching on and off of the power switch, thereby controlling the average amount of power delivered by the power switch to a load. Switching the power transistor on and off effectively divides its power output into discrete components.The average voltage and / or current supplied to a load can be controlled by rapidly switching the power transistor on and off. The longer the switch is on compared to the off periods, the higher the total power supplied to the load.

[0004] In many applications, various power transistors are configured in high-side and low-side configurations, and the switching on / off of the power transistors is synchronized to deliver the desired power to a switching node positioned between the high-side and low-side switches. Three-phase inverter circuits, for example, may include three different half-bridge circuits, each containing a high-side and a low-side power switch to control three different phase currents for a multi-phase electric motor.

[0005] It is often desirable or necessary to monitor the current through a motor, for example, as part of a control loop for motor control. A sense resistor is typically used for such current monitoring. Current sense resistors are relatively expensive components, and their use for current measurement in motor control can create challenges and limitations for the design of other circuit components. SUMMARY

[0006] In some aspects, a procedure is described. The procedure involves operating a bridge circuit in a freewheeling phase, during which a freewheeling current flows through a body diode of a power transistor in the bridge circuit. The procedure includes performing a first measurement during the freewheeling phase to determine the junction temperature of the power transistor. The procedure includes performing a second measurement during the freewheeling phase to determine the drain voltage of the power transistor.

[0007] In some aspects, a controller is described. The controller is configured to control a bridge circuit during a freewheeling phase, in which a freewheeling current flows through a body diode of a power transistor in the bridge circuit. The controller is configured to perform a first measurement during the freewheeling phase to determine the junction temperature of the power transistor. The controller is configured to perform a second measurement during the freewheeling phase to determine the drain voltage of the power transistor.

[0008] Several aspects of a system are described. The system includes a motor, a controllable bridge circuit to supply power to the motor, and a controller. The controller is configured to operate the bridge circuit in a freewheeling phase, during which a freewheeling current flows through a body diode of a power transistor in the bridge circuit. The controller is configured to perform a first measurement during the freewheeling phase to determine the junction temperature of the power transistor. The controller is configured to perform a second measurement during the freewheeling phase to determine the drain voltage of the power transistor. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram of a system configured to control a motor according to some embodiments. Fig. Figure 2 is a circuit diagram representing a bridge circuit according to some embodiments. Fig. Figure 3 is a timing diagram illustrating the operation of a controller for controlling a bridge circuit to supply energy to a motor and measure a load current, according to some embodiments. Fig. 4A- Fig. 4C are circuit diagrams that illustrate the operation of a bridge circuit in the respective phases of a low-side switching cycle of the bridge circuit. Fig. 5A- Fig. 5C are circuit diagrams that show the operation of a bridge circuit in the respective phases of a high-side switching cycle of the bridge circuit. Fig. Figure 6 is a circuit diagram showing an example of a three-phase bridge circuit that can be operated to determine a load current associated with at least one phase of the bridge circuit, according to some embodiments. Fig. Figure 7 is a graph showing three different current waveforms that correspond to the three phases of a three-phase electric motor. Fig. Figure 8 is a flowchart that illustrates an example of a method for measuring a load current of a bridge circuit according to some embodiments. DETAILED DESCRIPTION

[0009] Fig. Figure 1 is a block diagram of a system 100 configured to control an electric motor 140 according to some embodiments. The system 100 includes a controller 160 configured to control power transistors of a bridge circuit 120 to supply energy to the motor 140 from a power source 130. The bridge circuit 120 includes a high-side, comprising at least one high-side power transistor (HS power transistor), and a low-side, comprising at least one low-side power transistor (LS power transistor). The power transistors can be operated as a pair corresponding to one phase of the motor 140. In some examples, the electric motor 140 can be a two-phase electric motor, and the bridge circuit 120 can be configured as an H-bridge circuit with a high-side comprising a pair of HS transistors and a low-side comprising a pair of LS transistors.The high- and low-side power transistors of the bridge circuit 120 are connected synchronously to alternately supply energy with a first polarity to drive a first phase of the two-phase motor and with a second, opposite polarity (i.e., reverse motor control) to a second phase of the two-phase motor. In other examples, the bridge circuit 120 is configured with a high-side and a low-side, each containing three pairs of power transistors to supply energy to each of the three phases of a three-phase electric motor 140, each phase being 120 degrees out of phase with the other two phases.

[0010] The motor 140 can be a direct current (DC) motor, such as a brushless DC (BLDC) motor, a stepper motor, an AC motor, or any other type of motor commonly used in applications such as driving fans, opening and closing windows, opening and closing a sunroof, adjusting seat positions, operating pumps, control flaps, and many other processes in vehicles. In abstract terms, an electric motor converts electrical energy into mechanical energy. This is achieved by generating a dynamic magnetic field that changes the position of the motor's rotor. The dynamic magnetic field can be located in either the stator or the rotor of the motor 140. The motor 140 can be controlled to run at a constant speed, a constant torque, or to be driven in a defined position.

[0011] The speed of an electric motor 140 can depend on the applied voltage, the motor-specific electrical, magnetic, and mechanical properties, and the load torque. The drive of the motor 140 is implemented by power transistors, which can be semiconductor devices such as MOSFETs, bipolar transistors, or IGBTs. In other examples, the power transistors can be implemented with other materials, such as high-bandgap materials like gallium nitride (GaN) and / or silicon carbide (SiC). The power transistors can be connected using a bridge circuit 120, as in the example of Fig. Figure 1 shows how the power circuit is connected to motor 140. The bridge circuit 120 can be a half-bridge, a full bridge, an H-bridge, or an H-bridge. In another example, such as when motor 140 is a stepper motor, the bridge circuit 120 can include four half-bridge circuits. The bridge circuit 120 controls the operation of motor 140 by changing the connection to the power supply, the motor supply voltage and current (static or dynamic), and the freewheeling to discharge the motor coil. The power transistors of the bridge circuit 120 can either be set to a constant state (i.e., turned on to conduct current or turned off to conduct no current) or can be driven with pulse-width modulation signals, which allows very precise control of the turn-on and turn-off times of the power transistors. This can be used to implement a closed-loop control system.

[0012] In the example of Fig. 1. The controller 160 is coupled to control the bridge circuit 120 in order to supply energy to the motor 140, i.e. a load current I. L The controller 160 can include one or more processor(s) 162, which may be a microprocessor or any other type of processing component, to execute instructions stored in one or more memory component(s) 164 to generate the control signals. In some examples, the controller 160 is implemented as a microcontroller that includes the processor(s) 162 and the memory component(s) 164, which are housed together in a semiconductor package. In other examples, the one or more processors 162 and / or the one or more memory component(s) 164 can be implemented as discrete components or arranged otherwise to implement the functions described herein.

[0013] The controller 160 can be coupled to send control signals to one or more driver circuit(s) (in Fig. (1 not shown) to supply the control signal, which receives the control signal and generates amplified driver signals with sufficient current to switch the power transistors of the bridge circuit 120 on and off at high speeds. The control 160 causes the power transistors of the bridge circuit 120 to switch on and off to adjust the level of the load current I. L to control the one that is supplied to the engine 140.

[0014] In some examples, the controller 160 controls the bridge circuit 120 to drive the motor 140 based on feedback. Such feedback can include sensor information such as angular velocity, torque, and / or the rotational position of a rotor relative to a stator. In some examples, a load current I LThe 110V supplied to the motor can be measured as feedback. In some examples, a load current I can be used. L 110, which is supplied to the motor 140, shall be proportional to a torque generated by the motor 140.

[0015] In conventional motor control systems, the load current supplied to a motor can be determined by measuring the voltage across one or more dedicated sense resistors with a known resistance, coupled in series with a bridge circuit. Since the sense resistor sees the same magnitude of current as the motor, it can, in some cases, dissipate a significant amount of energy, negatively impacting the efficiency of the conventional motor control system. For example, such a resistor I 2Derive R-power, where I is the current and R is the resistance of the sense resistor. In some examples, using a sense resistor to measure a load current in a conventional motor control system can cause further power loss while the sense resistor is allowed time to warm up. In some examples, motor currents can range from a few amperes to hundreds of amperes. Accordingly, the size of a sense resistor, which is directly correlated with the resistance, can be chosen to be as small as possible to reduce the impact on efficiency. In some examples, a sense resistor that is too small (i.e., too small a resistance) can impair the measurability and / or resolution of measurements across the sense resistor's terminals.

[0016] The in Fig. The system 100 shown is uniquely configured to perform a resistanceless measurement of a load current I Lto implement. Instead of implementing a dedicated resistance component as a measuring resistor, as described above in relation to conventional motor control systems, the system 100 is configured to measure the load current I L to determine based on measurements taken on a power transistor 112 of the bridge circuit 120. For example, the controller 160 can perform an initial measurement 150 of the power transistor 112 to determine its temperature, for example by detecting a body voltage V. B of the power transistor 114. The controller 160 can use the specific temperature to determine a resistance (R). DSON -value of the power transistor 112. The controller 160 can also perform a second measurement 152 of the power transistor 112 to determine a drain voltage V. D to determine the power transistor 112.

[0017] The bridge circuit 120 can be used in a ON phase, in which a load current I L The system can be operated during a period of active operation (i.e., the bridge circuit 120 couples the motor 140 such that a current flows through the motor 240 from a power supply to ground) and a freewheeling phase in which a freewheeling current flows through a body diode of the power transistor 112. In some examples, the controller 160 performs the first measurement 150 and the second measurement 152 during the freewheeling phase. The freewheeling current can flow from a source to a drain of the power transistor 112 in some examples. In some examples, the power transistor is a first power transistor 112 of the bridge circuit 120, as in the example of Fig. Figure 1 shows that the freewheeling phase is defined based on the switching operation of a second power transistor 114 of the bridge circuit 120. In some examples, the freewheeling phase is initiated by turning off the second power transistor 114, which ends a turn-on phase of the bridge circuit 120. In other examples, the freewheeling phase ends when the second power transistor 114 is turned on to begin a turn-on phase of the bridge circuit 120.

[0018] In some examples, the freewheeling phase includes a passive part and an active part. The passive part can be described as a dead time of the power transistor 112, during which both the first power transistor 112 and the second power transistor 114 are switched off to prevent short circuits. In some examples, the passive part of the freewheeling phase is initiated by the switch-off of the second power transistor 114. In some examples, the passive part of the freewheeling phase ends and the active part of the freewheeling phase begins when the first power transistor 112 is switched on. In some examples, the active part of the freewheeling phase, in which the first power transistor 112 is switched on, can be described as an inductor discharge phase. In some examples, the active part of the freewheeling phase ends when the first power transistor 112 is switched off.In some examples, the passive part of the freewheeling phase precedes the active part of the freewheeling phase in a switching cycle, and the controller 160 performs the first measurement 150 before the second measurement 152 during the freewheeling phase of the switching cycle. In other examples, the passive part of the freewheeling phase follows the active part of the freewheeling phase in the switching cycle, and the controller 160 performs the first measurement 150 after the second measurement 152 during the freewheeling phase of the switching cycle.

[0019] In some examples, the controller 160 can be operated to perform the first measurement 150 and the second measurement 152 during a low-side freewheeling phase, in which a freewheeling current flows through a low-side transistor of the bridge circuit 120. According to such examples, the first power transistor 112 is a low-side transistor of the bridge circuit 120, and the second power transistor 114 is a high-side transistor of the bridge circuit 120, and the freewheeling current flows through a first low-side transistor and a second low-side transistor of the bridge circuit 120.

[0020] In other examples, the controller 160 can be operated to perform the first measurement 150 and the second measurement 152, as described herein, during a high-side freewheeling phase in which a freewheeling current flows through a high-side transistor of the bridge circuit 120. According to such examples, the first power transistor 112 is a high-side transistor of the bridge circuit 120, the second power transistor 114 is a low-side transistor of the bridge circuit 120, and the freewheeling current flows through a first high-side transistor and a second high-side transistor of the bridge circuit 120.

[0021] The controller 160 can use the first measurement 150 and the second measurement 152 to determine a load current I L to determine the junction temperature of the power transistor 112. As mentioned above, the controller 160 can use the first measurement 150 as an indication of the junction temperature of the power transistor 112. As in Fig. As shown in Figure 1, the controller 160 can include one or more processor(s) 162 to access one or more stored data structures, such as a lookup table, stored in one or more memory component(s) 164, which the one or more processors 162 can access. Such stored data can include body tension-V B -Measurements reflecting the temperature of power transistor 112, on R DSON -Values ​​for the power transistor 112 are displayed. The R DSON The values ​​represent the resistances of the power transistor 112 when the power transistor 112 is in an on-state and conducting current. The controller 160 can access the stored data to perform the first measurement 150 (the body voltage V). B ) on an R DSON -value for the power transistor 112.

[0022] The 160 controller can handle the R DSON-value (determined based on the first measurement 150) and the second measurement 152 (the recorded drain voltage V) D ) use to determine the load current I L to determine. For example, the load current I L based on the R DSON -value and the drain voltage V D determined according to the following equation (1): IL=VD / RDSON

[0023] Where I L The load current is V D the measured drain voltage of the first power transistor 112 (the second measurement 152) and R DSON is a single-resistance of the first power transistor 112 (determined based on the first measurement 150).

[0024] In some examples, the controller 160 can supply a load current I L based on measurements 150, 152, which were taken during a single switching cycle of the bridge circuit 120, determine a value of the load current I Lbased on the first and second measurements according to equation (1), as described above, determine and use the determined value as feedback to control the bridge circuit 120.

[0025] In some examples, the controller 160 can execute an iterative process to determine the load current I L based on performing the first and second measurements 150, 152 during the freewheeling phase of the bridge circuit 120, the controller 160 can determine an estimate of the junction temperature associated with the first power transistor 112, based on an assumed current level and the first measurement 150 (of the body voltage V). B of the first power transistor 112) and determine an R DSONThe value assigned to the first power transistor 112 is determined based on the estimated junction temperature. The controller 160 can then make a new assumption of the current level based on the determined RDS(on). DSON -value and the second measurement 152 (the drain voltage V) D of the first power transistor 112) and the controller 160 can choose between determining a new estimate of the load current I L , determining a new value of R DSON based on the first measurement 150 and the determination of the load current I L based on the new value of R DSON and the second measurement 152 (the drain voltage V D of the first power transistor 112). In some examples, the controller 160 can perform such iterations for N switching cycles, where N is a positive integer greater than 2. After N iterations, the controller 160 can make an accurate estimate of the load current I. L determine.

[0026] As mentioned above, the in Fig. The motor 140 shown in Figure 1 can be a two-phase motor or a three-phase motor configured to be driven as three separate phases separated by 120 degrees. According to examples where the motor is a three-phase motor, the bridge circuit 120 includes a high-side with three high-side power transistors HS1, HS2, and HS3, and a low-side with three low-side power transistors LS1, LS2, and LS3. According to these examples, the first and second measurements 150 and 152 at any of the high-side power transistors HS1, HS2, HS3, or any of the low-side power transistors LS1, LS2, LS3 of the bridge circuit 120 can be described as the one shown in Figure 1. Fig. The first power transistor 112 shown in Figure 1 is used. In other examples not shown here, a bridge circuit 120 can include any number of high-side and low-side transistors, and the controller can perform the first and second measurements 150, 152 during a freewheeling phase in which a freewheeling current flows through the body diode of the transistor under test (the one shown in Figure 1). Fig. 1 shown first transistor 112) flows.

[0027] In some examples, the controller 160 can perform the first and second measurements 150, 152 on the first power transistor 112 during a freewheeling phase of a three-phase bridge circuit. In some examples, the freewheeling phase is a high-side freewheeling phase, in which a freewheeling current flows through one or more of the high-side power transistors HS1, HS2, and HS3. According to these examples, the second power transistor 114 is at least one of the low-side power transistors LS1, LS2, or LS3. In some such examples, the controller 160 performs the first and second measurements 150, 152 during a freewheeling phase in which each of the low-side power transistors LS1, LS2, LS3 is switched off to isolate the high-side power transistors HS1, HS2 and HS3 from a ground reference, so that a freewheeling current flows through the high-side power transistors HS1, HS2 and HS3.

[0028] In some examples, the freewheeling current is a low-side freewheeling current flowing through the low-side transistors LS1, LS2, LS3. According to these examples, the second power transistor 114 is at least one of the high-side transistors HS1, HS2, and HS3. In some such examples, the controller 160 performs the first and second measurements 150, 152 during a freewheeling phase in which each of the high-side power transistors HS1, HS2, and HS3 is switched off to isolate the low-side power transistors LS1, LS2, LS3 from a current source 130, allowing a freewheeling current to flow through the low-side power transistors LS1, LS2, LS3.

[0029] In some examples, the controller 160 can perform the first and second measurements 150, 152 during a time period in which most or all of the freewheeling current flows through the power transistor 112 being measured. For example, the controller 160 can perform the first and second measurements 150, 152 on a low- or high-side transistor assigned to one phase of the three-phase motor with a load current of a first polarity (i.e., positive or negative) when the load currents assigned to the other two phases of the three-phase motor have a second, opposite polarity (i.e., negative or positive). In some examples, the controller 160 can perform the first and second measurements 150, 152 on a low- or high-side transistor assigned to one phase of the three-phase motor when load currents assigned to the other two phases cross each other.

[0030] In some examples, the system 100 can be uniquely configured to handle a load current I L The first and second measurements 150 and 152 on a power transistor (power transistor 112) of the bridge circuit 120 are to be determined by performing the first and second measurements 150 and 152. In some examples, performing the first and second measurements 150 and 152 on a power transistor of the bridge circuit 120 can be a resistanceless measurement of the load current I. LThis enables a method that is relatively simple compared to conventional techniques. Additionally, the system 100 is configured such that the controller 160 performs the first and second measurements 150, 152 during a freewheeling phase (a low-side and / or high-side freewheeling phase) of the bridge circuit 120. In some examples, performing the first and second measurements during a freewheeling phase can allow the first and second measurements 150, 152 to be performed relatively close together (e.g., within less than 100 microseconds, meaning that the second measurement 152 is performed less than 100 microseconds before or after the first measurement 150), which can allow the load current I Lis determined with a high degree of accuracy. In some examples, the first and second measurements 150, 160 can be performed closer together; for example, the first and second measurements 150, 160 can be performed within less than 50 microseconds, within less than 20 microseconds, or within less than 10 or less than 5 microseconds.

[0031] Fig. Figure 2 is a circuit diagram representing a bridge circuit 220 according to some embodiments. The bridge circuit 220 corresponds to an example of a bridge circuit 120, which can be controlled by a controller 160 to supply energy in the form of a load current I. L to supply power to drive a 240 motor. In the example of Fig. In Figure 2, the bridge circuit 220 is configured as an H-bridge circuit with a high-side transistor 221, which includes a first high-side transistor HS1 and a second high-side transistor HS2. Both the first high-side transistor HS1 and the second high-side transistor HS2 include a source terminal connected to a power supply V. S The first high-side transistor, HS1, includes a drain terminal that is coupled to a positive terminal of motor 240. The second high-side transistor, HS2, includes a drain terminal that is coupled to a negative terminal of motor 240.

[0032] In the example of Fig. The bridge circuit 220 further includes a low-side 223, which comprises a low-high-side transistor LS1 and a second low-side transistor LS2. Both the first low-side transistor LS1 and the second low-side transistor LS2 have a source terminal coupled to a ground reference. The first low-side transistor LS1 has a drain terminal coupled to a positive terminal of the motor 240, which in turn is coupled to the source terminal of the first high-side transistor HS1. The second low-side transistor LS2 has a drain terminal coupled to a negative terminal of the motor 240, which in turn is coupled to the source terminal of the second high-side transistor HS2.

[0033] In the example of Fig. 2. The transistors HS1, HS2, LS1 and LS2 can be switched between an on or conducting state and an off or non-conducting state to control the load current I. Lto control the power supplied to motor 240. Motor 240 in the example of Fig. 2 is a two-phase motor with stator windings configured to generate two magnetic fields 90 degrees apart to drive one or more corresponding rotor(s). As above in relation to Fig. As described in 1, a controller 160 can be configured to perform a first measurement 150 to determine a temperature associated with a power transistor of the bridge circuit 220, and to perform a second measurement 152 to determine a drain voltage of the power transistor during a freewheeling phase of the bridge circuit 220.

[0034] In some examples, the freewheeling phase is a low-side freewheeling phase, in which a freewheeling current flows through the low side 223 (i.e., the low-side transistors LS1 and LS2) of the bridge circuit 220. According to these examples, the in Fig. Figure 1 shows the first power transistor 112 as one of the low-side transistors LS1, LS2 of the bridge circuit 220, in particular the first low-side transistor LS1 in the example of Fig. 2. As in Fig. As shown in Figure 2, the controller 160 performs the first measurement of 250A by detecting a body voltage V. B of the first low-side transistor LS1 and performs the second measurement 252A by detecting a drain voltage V D of the first low-side transistor LS1. According to these examples, the one in Fig. Figure 1 shows the second power transistor 114, one of several of the high-side transistors HS1, HS2 of the bridge circuit, which is switched off to disconnect the low-side 223 from the power source V. S to decouple in order to initiate the low-side freewheeling phase, in particular the first high-side transistor HS1 of the bridge circuit 220 in the example of Fig. 2. The second high-side transistor HS2 can also be switched off during the high-side freewheeling phase.

[0035] In some examples, the freewheeling phase is a high-side freewheeling phase, in which a freewheeling current flows through the high-side 221 (i.e., the high-side transistors HS1 and HS2) of the bridge circuit 220. According to these examples, the in Fig. The first power transistor 112 shown is one of the high-side transistors HS1, HS2 of the bridge circuit 220, in particular the first high-side transistor HS1 in the example of Fig. 2. According to this example, the controller 160 performs the first measurement 250B by detecting a body voltage V B of the first high-side transistor HS1 and performs the second measurement 252A by detecting a drain voltage V D of the first high-side transistor HS1. According to these examples, the one in Fig. Figure 1 shows the second power transistor 114 connected to the first low-side transistor LS1 of the bridge circuit 220, which is switched off to initiate the high-side freewheeling phase. The second low-side transistor LS2 can also be switched off during the high-side freewheeling phase.

[0036] Fig. Figure 3 is a timing diagram illustrating the operation of a controller for controlling a bridge circuit to supply energy to a motor and measure a load current 310, according to some embodiments. The example of Fig. 3 can represent the operation of a controller 160, as in Fig. 1 shown to control the circuit breakers of a 220V bridge circuit, as in the example of Fig. 2 shown. The left side of Fig. Figure 3 shows a first and a second measurement of 250A and 252A, respectively, which are carried out during a low-side freewheeling phase of 301A of a switching cycle of 305A of the bridge circuit 220 when the load current 310 flows in a first direction. The right side of Fig. Figure 3 shows a first and a second measurement 250B, 252B, which are carried out during a high-side freewheeling phase 301B of a switching cycle 305B of the bridge circuit 220 when the load current 310 flows in a second direction that differs from the first direction.

[0037] Fig. 4A- Fig. 4C are circuit diagrams that illustrate the operation of a bridge circuit 420 in the respective phases of a low-side switching cycle 305A of the bridge circuit 420. The in Fig. 4A- Fig. The bridge circuit 420 shown in 4C can be used in Fig. The bridge circuit 220 shown in Figure 2 corresponds to this and includes a high-side 421 and a low-side 423, with the second high-side switch HS2 being off, so that no current flows through the second high-side switch HS2. In other examples, the circuit shown in Figure 2 corresponds to this. Fig. 4A- Fig. 4C shows bridge circuit 420 of an H-bridge circuit configured to drive the motor 240 in only one direction, which does not include a second high-side switch HS2.

[0038] Referring to the time diagram of Fig. 3. The bridge circuit can be operated in a single (i.e., active) phase before operation in the low-side freewheeling phase 301A shown. Fig. 4A represents an example of the bridge circuit 420, which is operated in a single-phase configuration. In the single-phase configuration, the first high-side transistor HS1 and the second low-side transistor LS2 are switched on, so that a load current 410 flows from a positive terminal to a negative terminal of the motor 240 from the power supply V. S flows to the ground reference. As in Fig. As shown in diagram 4A, in the on-phase the first low-side transistor LS1 is switched off, which decouples the positive terminal of motor 240 from the ground reference. In the example of Fig. 4A- Fig. 4C corresponds to the first low-side transistor LS1 and the first power transistor 112 of Fig. 1 and the first high-side transistor HS1 corresponds to the second power transistor 114 of Fig. 1.

[0039] Referring to the time diagram of Fig. At time t0, the low-side freewheeling phase 301A is initiated when the first high-side transistor HS1 is switched off, causing a freewheeling current 415A, 415B to flow through the low side 423 of the bridge circuit 420. As also in Fig. As shown in Figure 3, the low-side freewheeling phase 301A ends at time t5 when the first high-side transistor HS1 is switched on, which begins a subsequent on-phase, as in the example of Fig. 4A shown. As in Fig. As shown in Figure 3, a controller 160 performs a first measurement of 250A (e.g., to detect a body voltage V). B ) and a second measurement 252A (e.g. to detect a drain voltage V) D ) during the low-side freewheeling phase, 301A passes through to carry a load current I L to determine the engine 240.

[0040] As in Fig. As shown in Figure 3, the low-side freewheeling phase 301A includes one or more passive part(s) 302A / 302A' and an active part 303A. As shown in Fig. As shown in Figure 3, the passive part 302A corresponds to the time period between time t0, when the first high-side transistor HS1 is switched off, and time t2, when the first low-side transistor LS1 is switched on. As shown in Fig. As shown in Figure 3, the active part 303A corresponds to the time period between time t2, when the first low-side transistor LS1 is switched on, and time t4, when the first low-side transistor LS1 is switched off. As shown in Fig. As shown in Figure 3, the passive part 302A' is defined as the time period between time t4, when the first low-side transistor LS1 is switched off at time t4, and time t5, when the first high-side transistor HS1 is switched on, which terminates the low-side freewheeling phase 301A.

[0041] Referring to the circuit diagram of Fig. 4B, in the passive part(s) 302A, 302A' of the low-side freewheeling phase 301A, the first high-side switch HS1 is switched off, which switches off the power supply V S decoupled from the positive terminal of motor 240. As in Fig. As shown in Figure 4B, in the passive part(s) 302A, 302A' of the low-side freewheeling phase 301A, the first low-side transistor LS1 is switched off and the second low-side transistor LS2 is switched on. As shown in Fig. As shown in Figure 4B, a freewheeling current of 415A flows through the low-side 423 of the bridge circuit 420 from the positive to the negative terminal of the motor 240, from the drain to the source of the second low-side transistor LS2, and through the body diode of the first low-side transistor LS1 in the passive part(s) 302A, 302A' of the low-side freewheeling phase 301A. As shown in Fig. 4B and Fig. As shown in Figure 3, the controller 160 can perform a first measurement 250A at a time t1, which lies during the passive part(s) 302A, 302A' of the low-side freewheeling phase 301A, for example to measure a body voltage V B to measure the temperature of the first power transistor 112, which the controller 160 can use to measure the temperature of the first low-side transistor LS1 and / or an R DSON -value for the first low-side transistor LS1.

[0042] Referring to the circuit diagram of Fig. In the active part 303A of the low-side freewheeling phase 301A, the first high-side transistor HS1 is switched off, the second low-side transistor LS2 is switched on, and the first low-side transistor LS1 is switched on. As in Fig. As shown in Figure 4C, in the active part 303A of the low-side freewheeling phase 301A, a freewheeling current 415B flows through the low-side 423 of the bridge circuit 420 from the positive to the negative terminal of the motor 240, from the drain to the source of the second low-side transistor LS2, from the source to the drain of the first low-side transistor LS1, and through the body diode of the first low-side transistor LS1. As shown in Fig. 4C and in Fig. As shown in Figure 3, the controller 160 can perform a second measurement 252A during the active part 303A of the low-side freewheeling phase 301A, for example to measure a drain voltage V. D to determine the first low-side transistor LS1.

[0043] In some examples, the first measurement of 250A can be carried out during the passive part 302A before the second measurement of 252A is carried out in the active part 303A, as in the example of Fig. Figure 3 shows that in other examples not shown, the first measurement 250A can be performed during the passive part 302A' after the second measurement 252A has been performed. Regardless, in some examples, both the first measurement 250A and the second measurement 252A are performed within a short time of each other, for example, during the same switching cycle 305A of the bridge circuit 220.

[0044] As mentioned above, the right side of Fig. 3 a first and a second measurement 250B, 252B, which are carried out during a high-side freewheeling phase 301B of a switching cycle 305B of the bridge circuit 220. Fig. 5A- Fig. 5C are circuit diagrams that illustrate the operation of a 520 bridge circuit in the respective phases of a high-side switching cycle 305B of the 520 bridge circuit. The diagrams shown in Fig. 5A- Fig. The bridge circuit 520 shown in 5C can be used in Fig. The bridge circuit 220 shown in Figure 2 corresponds to the circuit and includes a high-side 521 and a low-side 523, with the second low-side switch LS2 being off, so that no current flows through the second low-side switch LS2. In other examples, the circuit shown in Figure 2 corresponds to the bridge circuit 220. Fig. 5A- Fig. Figure 5C shows a bridge circuit 520 of an H-bridge circuit configured to drive the motor 240 in only one direction, which does not include a second low-side switch LS2.

[0045] Referring to the time diagram of Fig. 3. The bridge circuit can be operated in a one-on (i.e., active) phase before operation in the high-side freewheeling phase 301B shown. Fig. 5A represents an example of the 520 bridge circuit operating in single-phase mode. In single-phase mode, the second high-side transistor HS2 and the first low-side transistor LS1 are switched on, resulting in a load current I. L510 Current from a negative terminal to a positive terminal of the motor 240 from the power supply V S flows to the ground reference. As in Fig. As shown in 5A, in the one-phase the second high-side transistor HS1 is switched off, which disconnects the positive terminal of the motor 240 from the power supply V. S decoupled. As in Fig. 5A- Fig. As shown in Figure 5C, the first high-side transistor HS1 corresponds to the first power transistor 112 of Fig. 1 and the first low-side transistor LS1 corresponds to the second power transistor 114 of Fig. 1.

[0046] Referring to the time diagram of Fig. At time t0*, the high-side freewheeling phase 301B is initiated when the first low-side transistor LS1 is switched off, causing a freewheeling current 515A, 515B to flow through the high-side 521 of the bridge circuit 520. As also in Fig. As shown in Figure 3, the high-side freewheeling phase 301B ends at time t4* when the first low-side transistor LS1 is switched on, which begins a subsequent on-phase, as in the example of Fig. 5A shown. As in Fig. As shown in Figure 3, a controller 160 performs a first measurement 250B and a second measurement 252B during the high-side freewheeling phase 301B to determine a load current I L 510 of the 240 engine to determine.

[0047] As in Fig. As shown in Figure 3, the high-side freewheeling phase 301B includes one or more passive part(s) 302B / 302B' and one active part 303B. As shown in Fig. As shown in Figure 3, the passive part 302B corresponds to the time period between time t0*, when the first low-side transistor LS1 is switched off, and time t2*, when the first high-side transistor HS1 is switched on. As shown in Fig. As shown in Figure 3, the active part 303B corresponds to the time period between time t2*, when the first high-side transistor HS1 is switched on, and time t4*, when the first high-side transistor HS1 is switched off. As shown in Fig. As shown in Figure 3, the passive part 302B' is defined as the time period between time t4*, when the first high-side transistor HS1 is switched off at time t4*, and time t5*, when the first low-side transistor LS1 is switched on, which terminates the high-side freewheeling phase 301B.

[0048] Referring to the circuit diagram of Fig. In the passive part(s) 302B, 302B' of the high-side freewheeling phase 301B, the first low-side transistor LS1 is switched off, thus decoupling the positive terminal of the motor 240 from the ground reference. As in Fig. As shown in Figure 5B, in the passive part(s) 302B, 302B' of the high-side freewheeling phase 301B, the first high-side transistor HS1 is switched off and the second high-side transistor HS2 is switched on. As shown in Fig. As shown in Figure 5B, a freewheeling current of 515A flows in the passive part(s) 302B, 302B' of the high-side freewheeling phase 301B through the high-side 521 of the bridge circuit 520 from the drain to the source of the second high-side transistor HS2, from the negative to the positive terminal of the motor 240, and through the body diode of the first high-side transistor HS1. As shown in Fig. 5B and in Fig. As shown in Figure 3, the controller 160 can perform a first measurement 250B at a time t1* which lies during the passive part(s) 302B, 302B' of the high-side freewheeling phase 301B, for example to measure a body tension V B to measure the temperature and / or resistance of the first high-side transistor HS1 DSON -value of the first high-side transistor HS1.

[0049] Referring to the circuit diagram of Fig. At step 5C, in the active part 303B of the high-side freewheeling phase 301B, the first high-side transistor HS1 is switched on, the second high-side transistor HS2 is switched on, and the first low-side transistor LS1 is switched off. As in Fig. As shown in Figure 5C, a freewheeling current 515B flows in the active part 303B of the high-side freewheeling phase 301B from the drain to the source of the second high-side transistor HS2, from the negative to the positive terminal of the motor 240, from the source to the drain of the first high-side transistor HS1, and through the body diode of the first high-side transistor HS1. As shown in Fig. 4C and in Fig. As shown in Figure 3, the controller 160 can perform a second measurement 252B during the active part 303B of the high-side freewheeling phase 301B, for example to measure a drain voltage V. D to determine the first high-side transistor HS1.

[0050] In some examples, the first measurement 250B can be performed during the passive part 302B before the second measurement 252B is performed in the active part 303B, as in the example of Fig. Figure 3 shows that in other examples not shown, the first measurement 250B can be performed during the passive part 302B', after the second measurement 252B has been performed. Regardless, in some examples, both the first measurement 250B and the second measurement 252B are performed within a short time of each other, for example, during the same switching cycle 305A of the bridge circuit 220.

[0051] As in the example of Fig. As shown in Figure 3, a controller 160, as described herein, can perform a first measurement 150 and a second measurement 152 during a freewheeling phase of the bridge circuit 220. These measurements can be 250A and 252A, taken during a low-side freewheeling phase 301A of the bridge circuit 220. In other examples, the first and second measurements 150 and 152 can also include, or instead include, measurements 250B and 252B, taken during a high-side freewheeling phase 301B of the bridge circuit 220. In some examples, the controller can perform the respective first measurements 250A and 250B during a freewheeling phase of a different switching cycle 305A and 305B than the second measurements 252A and 252B. In other examples, as in the diagram of Fig. As shown in Figure 3, the controller 160 can perform the respective first measurements 250A, 250B during the same switching cycle as the second measurements 252A, 252B. In some examples, the controller 160 can perform the respective first measurements 250A, 250B close in time to the second measurements 252A, 252B. For example, the controller 160 can perform the second measurements 252A, 252B within 100 microseconds of performing the first measurements 250A, 252B. In some examples, the first and second measurements 150, 160 can be performed within less than 50 microseconds, within less than 20 microseconds, or within less than 10 or less than 5 microseconds.

[0052] In some examples, a controller 160, as described herein, can perform the first measurement 250A and the second measurement 252A during a low-side freewheeling phase 301A of a high-side switching cycle, and perform the first measurement 250B and the second measurement 252B during a subsequent high-side freewheeling phase 301B, as shown in the timing diagram of Fig. 3 shown, and both measurements are used to determine the load current I L to determine 210A, 210B. In other examples, the controller 160 can only perform the first measurement 250A and the second measurement 252A during the low-side freewheeling phases and not the first measurement 250B and the second measurement 252B during a high-side freewheeling phase 301B. Similarly, the controller can only perform the first measurement 250B and the second measurement 252B during the high-side freewheeling phases and not the first measurement 250A and the second measurement 252A during the low-side freewheeling phase 301A.

[0053] The in the Fig. 4A-4C and Fig. The examples shown in sections 5A-5C are provided for illustrative purposes and are not intended to be restrictive. An average person will recognize that the bridge circuits 420 and 520 shown are symmetrical and can be operated in opposite directions as described. For example, the Fig. 4A- Fig. 4C represents a low-side freewheeling phase that follows a one-way phase in which the first high-side transistor HS1 and the second low-side transistor LS2 operate as active transistors, creating a current path from the current source Vs to the ground reference through the motor 240 (from the positive terminal to the negative terminal of the motor). According to these examples, the first low-side transistor LS1 corresponds to the first power transistor 112 of Fig. 1, the first high-side transistor HS1 corresponds to the second power transistor 114 of Fig. Measurements 1 and 152, the first and second measurements, are performed with respect to the first low-side transistor LS1. In other examples not shown, a low-side freewheeling phase follows a one-way phase in which the second high-side transistor HS2 and the first low-side transistor LS1 operate as active transistors, providing a current path from the current source V. S to the ground reference through motor 240 (from the negative terminal to the positive terminal of the motor). According to these examples, the second low-side transistor LS2 corresponds to the first power transistor 112 of Fig. 1, the second high-side transistor HS2 corresponds to the second power transistor 114 of Fig. 1 and the first and second measurements 150, 152 are performed with respect to the second low-side transistor LS2.

[0054] As another example, the Fig. 5A- Fig. 5C represents a high-side freewheeling phase that follows a one-side phase in which the second high-side transistor HS2 and the first low-side transistor LS1 operate as active transistors, providing a current path from the current source V S to generate a ground reference through motor 240 (from the negative terminal to the positive terminal of the motor). According to these examples, the first high-side transistor HS1 corresponds to the first power transistor 112 of Fig. 1, the first low-side transistor LS1 corresponds to the second power transistor 114 of Fig. Measurements 1 and 152, the first and second measurements, are performed with respect to the first high-side transistor HS1. In other examples not shown, a high-side freewheeling phase follows a one-way phase in which the first high-side transistor HS1 and the second low-side transistor LS2 operate as active transistors, providing a current path from the current source V. Sto generate a ground reference through motor 240 (from the positive terminal to the negative terminal of the motor). According to these examples, the second high-side transistor HS2 corresponds to the first power transistor 112 of Fig. 1, the second low-side transistor LS2 corresponds to the second power transistor 114 of Fig. 1 and the first and second measurements 150, 152 are performed with respect to the second high-side transistor HS2.

[0055] In some examples, the controller 160 can execute an iterative process to determine the load current I L based on performing the first and second measurements during the freewheeling phase of the bridge circuit 220. In particular, the controller 160 can estimate the junction temperature associated with the first power transistor 112, based on an assumed current level and the first measurement of 250A, 250B (the body voltage V). Bof the first power transistor 112) and determine an R DSON The value assigned to the first power transistor 112 is determined based on the specified estimate of the junction temperature. The controller 160 can assume a current level based on the specified R DSON -value and the second measurement 252A, 252B (the drain voltage V) D of the first power transistor 112). The controller 160 can determine a new estimate of the load current I over several switching cycles. L , determining a new value of R DSON based on the first measurement 250A, 250B and determining the load current I L Based on the second measurement, 252A and 252B are iterated. In some examples, the controller 160 can perform such iterations for N switching cycles, where N is a positive integer greater than 2. After N iterations, the controller 160 can make an accurate estimate of the load current I. Ldetermine.

[0056] Fig. Figure 6 is a circuit diagram showing an example of a three-phase bridge circuit 620 that can be operated to determine a load current assigned to at least one phase of the bridge circuit 620, according to some embodiments. The bridge circuit 620 corresponds to the one shown in Figure 6. Fig. 1. Bridge circuit 120 shown. In the example of Fig. Figure 6 is a three-phase motor 640 modeled by three inductors. A first inductor represents a first phase 674 of the motor 640, a second inductor represents a second phase 676 of the motor 640, and a third inductor represents a third phase 678 of the motor 640.

[0057] As in Fig. As shown in Figure 6, the bridge circuit 620 includes a high-side 621 and a low-side 623. The high-side 621 includes three high-side power transistors H1, H2, and H3. The low-side 623 includes three low-side power transistors L1, L2, and L3, which are configured to be switched synchronously with the three high-side transistors H1, H2, and H3 to supply a load current to each phase 674, 676, 678 of the motor 640. According to the example of Fig. 6. The first high-side transistor HS1 and the first low-side transistor LS1 are operated to supply a load current I to the first phase 676 of the motor. L 1. The second high-side transistor H2 and the second low-side transistor L2 can be operated to supply a load current I to the second phase 678 of the motor. L 2. The third high-side transistor H3 and the third low-side transistor L3 can be operated to supply a load current I to the second phase 678 of the motor. L 3 to supply.

[0058] Like the in Fig. In the bridge circuit 120 shown, the controller 160 can be configured to perform a first and a second measurement 150, 152 on one or more of the high-side transistors H1, H2, H3 and / or one or more of the low-side transistors L1, L2, L3 during a freewheeling phase in which a freewheeling current flows through a body diode of the respective transistor.

[0059] For example, the freewheeling phase can be a low-side freewheeling phase, in which a freewheeling current flows through one or more of the low-side transistors L1, L2, L3. According to these examples, the first power transistor 112 corresponds to Fig. 1 to the one or more low-side transistors L1, L2, L3 to be measured. According to this example, the second power transistor 114 corresponds to Fig. 1. One or more of the high-side transistors H1, H2, H3 are switched off to decouple the high-side 621 from the low-side 623, allowing a freewheeling current to flow through the one or more low-side 623 transistors. A controller 160 can be configured to perform the first measurement 150 to determine a body voltage V. B to detect the voltage of the transistor under test during a passive part of the low-side freewheeling phase. The controller 160 can be configured to perform the second measurement 152 to obtain a drain voltage V. D to detect the transistor being measured during an active part of the low-side freewheeling phase.

[0060] As another example, the freewheeling phase can be a high-side freewheeling phase, in which a freewheeling current flows through one or more of the high-side transistors H1, H2, H3. According to these examples, the first power transistor 112 corresponds to Fig. 1 to the one or more high-side transistors H1, H2, H3 to be measured. According to this example, the second power transistor 114 corresponds to Fig. 1. One or more of the low-side transistors L1, L2, L3 are switched off to decouple the low-side 623 from the high-side 621, allowing a freewheeling current to flow through the one or more high-side transistors H1, H2, H3 to be measured. A controller 160 can be configured to perform the first measurement 150 to determine a body voltage V. B to detect the voltage of the transistor under test during a passive part of the high-side freewheeling phase. The controller 160 can be configured to perform the second measurement 152 to obtain a drain voltage V. D to capture the transistor being measured during an active part of the high-side freewheeling phase.

[0061] In some examples, the controller 160 can, regardless of whether the bridge circuit is a three-phase bridge circuit 620, as in Fig. Figure 6 shows a two-phase bridge circuit 220, as in Fig. 2 shown, or any other type of bridge circuit including any number of high-side and low-side transistors, can be configured to perform the first and second measurements at a specific power transistor based on the direction of current flow to the motor. For example, controller 160 can perform the first and second measurements 150, 152 at the third low-side transistor LS3 when the current I L Current 3 flows from motor 640 to bridge circuit 620, as shown in Fig. 6 shown. In other examples not shown in Fig. As shown in Figure 6, the controller 160 can perform the first and second measurements 150, 152 on the third high-side transistor HS3 when the current I L3 in the opposite direction from the bridge circuit 620 to the motor 640. In other examples, the controller 160 can operate in reverse and perform the first and second measurements 150, 152 at the third high-side transistor HS3 when the current flows from the motor 640 to the bridge circuit 620, and / or perform the first and second measurements 150, 152 at the third low-side transistor LS3 when the current I L Current flows in the opposite direction from the bridge circuit 620 to the motor 640. The same principle can be applied to any of the three phases of the circuit. Fig. The bridge circuit 620 shown in Figure 6, or any other bridge circuit not explicitly shown and / or described here and containing a variety of high-side and low-side transistors, may be used.

[0062] Fig. Figure 7 is a graph showing three different current waveforms that are assigned to the three phases 674, 676, 678 of a three-phase electric motor. Fig. 7 represents a relative time control for the controller 160 to perform a first measurement 150 and a second measurement 152 for a in Fig. The three-phase bridge circuit 620 shown in Figure 6 is used to perform the measurement. In some examples, the controller 160 can perform the first measurement 150 and the second measurement 152 during a freewheeling phase of one or more of the power transistors HS1, HS2, HS3, LS1, LS2, LS3. The example of Fig. 7 shows a current signal I L 1 of the first phase, which is supplied to the first phase 674, a current signal I L 2 of the second phase, which is supplied to the second phase 676, and a current signal I L 3 of the third phase, which is supplied to the third phase 678. According to this disclosure, the control 160 can perform the first measurement 150 (to obtain a body voltage V). Bto detect one of the circuit breakers) and the second measurement 152 (to measure a drain voltage V) D to detect one of the power switches) during a freewheeling phase in which a freewheeling current flows through the power transistor to be measured.

[0063] In some examples, the controller 160 can perform the first measurement 150 and the second measurement 152 at a time when it is known that all or most of a high-side or low-side freewheeling current is flowing through this power transistor. For example, the controller 160 can measure the load current I L 3 of the in Fig. To measure the third phase 678 shown in Figure 6, the first measurement 150 and the second measurement 152 are performed during a low-side freewheeling phase 301A, i.e., at a time when most or all of the high-side transistors HS1, HS2, and HS3 are switched off. This causes a freewheeling current to flow between the third low-side transistor LS3 and the second low-side transistor LS2, as well as a freewheeling current between the third low-side transistor LS3 and the first low-side transistor LS1. The controller 160 can perform the first measurement 250A during a passive part 302A, 302A' of the freewheeling phase 301A and the second measurement 252A during an active part 303A of the freewheeling phase 301A, as shown in the timing diagram of Figure 6. Fig. 3 shown.

[0064] As another example, the controller 160 can be used to control the load current I L 3 of the in Fig. To measure the third phase 678 shown in Figure 6, perform the first measurement 250B and the second measurement 250B during a high-side freewheeling phase 301B, as in the example of Fig. Figure 3 shows that at a time when most or all of the low-side transistors LS1, LS2, and LS3 are switched off, a freewheeling current flows between the third high-side transistor HS3 and the second high-side transistor HS2, and a freewheeling current flows between the third high-side transistor HS3 and the first high-side transistor HS1. The controller 160 can perform the first measurement 250B during a passive part 302B, 302B' of the high-side freewheeling phase 301B and the second measurement 252B during an active part 303B of the high-side freewheeling phase 301B.

[0065] In some examples, a controller 160 can be configured to perform the first measurement 150 and the second measurement 152 to determine a load current I. L 1, IL 2, I L 3 to determine for each respective phase 674, 676, 678 of the bridge circuit 620. With reference to Fig. 7. In some examples, the controller 160 can perform the first measurement 150 and the second measurement 152 at a time when it is known that all or most of a high-side or low-side freewheeling current is flowing through this power switch. For a high-side transistor HS3, which is subject to the current I L 3 is assigned to the third phase, this time can be during window W2 in Fig. 7 occur when the current I L 3 of the third phase is positive and the phase currents I L 2 and I11 are negative. In some examples, the controller 160 can take the first measurement 150 and the second measurement 152 for the circuit breaker LS3 with the current I. L 3 of the third phase at or near time 36, at which the phase currents I L 2 and I11 lie at an intersection point.

[0066] Similarly, the 160 control unit can be cited as another example with reference to Fig. 7 the first measurement 150 and the second measurement 152, which correspond to a current I L The operations assigned to the second phase 2 are performed at a time when all or most of a freewheeling current flows through the second low-side transistor LS2. This time can correspond to window W1 when the current I L 2 of the second phase is negative and the phase currents I L 3 and I11 are positive. In some examples, the controller 160 can take the first measurement 150 and the second measurement 152 during a freewheeling phase, which corresponds to the current I. L 2 of the second phase, to be carried out at or near time 38, at which the phase currents I L 3 and I11 lie at an intersection point.

[0067] In some examples, the controller 160 can execute an iterative process to determine the load currents I L 1, IL 2 and / or I L 3. Based on performing the first and second measurements 150, 152 during the freewheeling phase of the bridge circuit 620, the controller 160 can determine an estimate of the junction temperature associated with a power circuit of the bridge circuit 620, based on an assumption of a current level and the first measurement 150 (of the body voltage V). B of the power transistor) determine and a R DSON The value assigned to the power transistor is determined based on the specified estimate of the junction temperature. The controller 160 can assume a current level based on the specified RDS(on). DSON -value and the second measurement 150 (the drain voltage V) D of the first power transistor). The controller 160 can choose between determining a new estimate of the load current I. L , determining a new value of R DSONbased on the first measurement 150 and the determination of the load current I L Based on the second measurement, 152 iterations are performed. In some examples, the controller can perform 160 such iterations for N switching cycles, where N is a positive integer greater than 2. After N iterations, the controller can make an accurate estimate of the load current I. L 1, I L 2 and / or I L 3 determine.

[0068] Fig. Figure 8 is a flowchart illustrating an example of a method for measuring the load current of a bridge circuit according to some embodiments. As shown in Fig. As shown in Figure 8, the method at 801 involves operating a bridge circuit 120 in a freewheeling phase 301A, 301B, in which a freewheeling current flows through a body diode of a power transistor 112 of the bridge circuit 120. As shown in Fig. As shown in Figure 8, the procedure further includes, at Figure 802, performing a first measurement 150 (e.g., to determine body tension V). B of the power transistor 112) during the freewheeling phase 301A, 301B, to determine a junction temperature of the power transistor. As also in Fig. As shown in Figure 8, the procedure further includes, at Figure 803, performing a second measurement 152 during the freewheeling phase 301A, 301B to determine a drain voltage of the power transistor 112.

[0069] In some examples, the procedure further includes performing the first measurement 150 during a passive part 302A, 302A', 302B, 302B' of the free-running phase. In some examples, the procedure further includes performing the second measurement 152 during an active part 302A, 302B of the free-running phase 301A, 301B.

[0070] In some examples, the power transistor is a first power transistor 112 of the bridge circuit 120, and the procedure further includes performing the first measurement 150 after a second power transistor 114 of the bridge circuit 120 is switched off and before the first power transistor 112 is switched on. In some examples, the procedure further includes performing the second measurement 152 after the first power transistor 112 is switched on and before the first power transistor 112 is switched off. In some examples, the freewheeling phase is a low-side freewheeling phase 301A, in which the freewheeling current 415A flows through a low side of the bridge circuit 120, the first power transistor is a low-side transistor of the bridge circuit 120, and the second power transistor is a high-side transistor of the bridge circuit 120.In some examples, the freewheeling phase is a high-side freewheeling phase 301B, in which the freewheeling current 415B flows through a high-side 221 of the bridge circuit 120, the first power transistor 112 is a high-side transistor of the bridge circuit 120, and the second power transistor 114 is a low-side transistor of the bridge circuit 120.

[0071] In some examples, the procedure further involves performing the second measurement less than 10 microseconds within (i.e., before or after) the first measurement. In some examples, the procedure further involves performing both the first and second measurements during the freewheeling phase of a single switching cycle of the bridge circuit. In some examples, performing the first measurement involves detecting a voltage drop across the drain and source terminals of the power transistor 112, and performing the second measurement involves measuring a voltage drop across a body diode of the power transistor 112.

[0072] In some examples, the procedure further involves using a junction temperature determined based on the first measurement of 150 to calculate an R DSON to determine the power transistor 112, and using the second measurement 152 and the determined RDSON of the power transistor 112, in order to drive a load current I L to determine the bridge circuit 120. clauses

[0073] Clause 1. Method, comprising: operating a bridge circuit in a freewheeling phase in which a freewheeling current flows through a body diode of a power transistor of the bridge circuit; performing a first measurement during the freewheeling phase to determine a junction temperature of the power transistor; and performing a second measurement during the freewheeling phase to determine a drain voltage of the power transistor.

[0074] Clause 2. Procedure according to Clause 1, further comprising: performing the first measurement during a passive part of the freewheeling phase; and performing the second measurement during an active part of the freewheeling phase.

[0075] Clause 3. Method according to one of claims 1 and 2, wherein the power transistor is a first power transistor of the bridge circuit, and further comprising: performing the first measurement after a second power transistor of the bridge circuit is switched off and before the first power transistor is switched on.

[0076] Clause 4. Procedure according to Clause 3, further comprising: performing the second measurement after switching on the first power transistor and before switching off the first power transistor.

[0077] Clause 5. Method according to one of Clauses 3 and 4, wherein the freewheeling phase is a low-side freewheeling phase in which the freewheeling current flows through a low side of the bridge circuit, the first power transistor is a low-side transistor of the bridge circuit and the second power transistor is a high-side transistor of the bridge circuit.

[0078] Clause 6. Method according to any of Clauses 3-5, wherein the freewheeling phase is a high-side freewheeling phase in which the freewheeling current flows through a high-side of the bridge circuit, the first power transistor is a high-side transistor of the bridge circuit and the second power transistor is a low-side transistor of the bridge circuit.

[0079] Clause 7. Procedure according to any of Clauses 1-6, further comprising: performing the second measurement less than 10 microseconds within the performance of the first measurement.

[0080] Clause 8. Procedure according to any of Clauses 1-7, further comprising: performing the first measurement and the second measurement during the freewheeling phase of a single switching cycle of the bridge circuit.

[0081] Clause 9. The procedure according to Clause 8, further comprising one or more of: performing the first measurement before the second measurement during the switching cycle; and performing the second measurement before the first measurement during the switching cycle.

[0082] Clause 10. Method according to any of Clauses 1-9, wherein performing the first measurement includes measuring a voltage drop across drain and source terminals of the power transistor and the second measurement includes measuring a voltage drop across a body diode of the power transistor.

[0083] Clause 11. Procedure according to any one of Clauses 1-10, further comprising: using the junction temperature determined on the basis of the first measurement to calculate an R DSON to determine the power transistor; and using the second measurement and the determined R DSON of the power transistor to determine a load current of the bridge circuit.

[0084] Clause 12. Control, configured to: control a bridge circuit in a freewheeling phase in which a freewheeling current flows through a body diode of a power transistor of the bridge circuit; perform a first measurement during the freewheeling phase to determine a junction temperature of the power transistor; and perform a second measurement during the freewheeling phase to determine a drain voltage of the power transistor.

[0085] Clause 13. Control according to Clause 12, wherein the control is configured to: perform the first measurement during a passive part of the freewheeling phase; and perform the second measurement during an active part of the freewheeling phase.

[0086] Clause 14. Control according to one of Clauses 12 and 13, wherein the control is configured to: perform the second measurement less than 10 microseconds within the performance of the first measurement.

[0087] Clause 15. Control according to one of clauses 12-14, wherein the control is configured to: perform the first measurement and the second measurement during the freewheeling phase of a single switching cycle of the bridge circuit.

[0088] Clause 16. Control according to any of Clauses 12-15, wherein the control is configured to: use the junction temperature determined based on the first measurement to calculate an R DSON to determine the power transistor; and using the second measurement and the determined R DSON of the power transistor to determine a load current of the bridge circuit.

[0089] Clause 17. System comprising: a motor; a bridge circuit that is controllable to supply energy to the motor; and a controller configured to: operate a bridge circuit in a freewheeling phase in which a freewheeling current flows through a body diode of a power transistor of the bridge circuit; perform a first measurement during the freewheeling phase to determine a junction temperature of the power transistor; and perform a second measurement during the freewheeling phase to determine a drain voltage of the power transistor.

[0090] Clause 18. System according to Clause 17, wherein the controller is configured to: perform the first measurement during a passive part of the freewheeling phase; and perform the second measurement during an active part of the freewheeling phase.

[0091] Clause 19. System according to one of Clauses 17 and 18, wherein the controller is configured to: perform the second measurement less than 10 microseconds within the performance of the first measurement.

[0092] Clause 20. System according to one of clauses 17-19, wherein the controller is configured to: perform the first measurement and the second measurement during the freewheeling phase of a single switching cycle of the bridge circuit.

[0093] Clause 21. System according to any of clauses 17-20, wherein the controller is configured to: use the junction temperature determined based on the first measurement to calculate an R DSON to determine the power transistor; and using the second measurement and the determined R DSON of the power transistor to determine a load current of the bridge circuit.

[0094] Although this invention has been described with reference to illustrative embodiments, this description is not intended to be restrictive. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to a person skilled in the art with reference to the description. It is therefore intended that the appended claims include such modifications or embodiments.

Claims

[1] Procedure, encompassing: Operating a bridge circuit (120, 220, 420, 520, 620) in a freewheeling phase (301A, 301B) in which a freewheeling current flows through a body diode of a power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3) of the bridge circuit (120, 220, 420, 520, 620); Performing an initial measurement (150, 250A, 250B) during the freewheeling phase (301A, 301B) to determine a junction temperature of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3); and Performing a second measurement (152, 252A, 252B) during the freewheeling phase (301A, 301B) to determine a drain voltage of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3). [2] The method of claim 1, further comprising: Performing the first measurement (150, 250A, 250B) during a passive part of the freewheeling phase (301A, 301B); and Performing the second measurement (152, 252A, 252B) during an active part of the freewheeling phase (301A, 301B). [3] Method according to one of claims 1 and 2, wherein the power transistor is a first power transistor (112) of the bridge circuit (120, 220, 420, 520, 620), and further comprising: Performing the first measurement (150, 250A, 250B) after a second power transistor (114) of the bridge circuit (120, 220, 420, 520, 620) is switched off and before the first power transistor (112) is switched on. [4] The method of claim 3, further comprising: Performing the second measurement (152, 252A, 252B) after switching on the first power transistor (112) and before switching off the first power transistor (112). [5] Method according to one of claims 3 and 4, wherein the freewheeling phase (301A, 301B) is a low-side freewheeling phase in which the freewheeling current flows through a low-side (223, 423, 523, 623) of the bridge circuit (120, 220, 420, 520, 620), the first power transistor (112) is a low-side transistor of the bridge circuit (120, 220, 420, 520, 620) and the second power transistor (114) is a high-side transistor of the bridge circuit (120, 220, 420, 520, 620). [6] Method according to any one of claims 3-5, wherein the freewheeling phase (301A, 301B) is a high-side freewheeling phase in which the freewheeling current flows through a high-side (221, 421, 521, 621) of the bridge circuit (120, 220, 420, 520, 620), the first power transistor (112) is a high-side transistor of the bridge circuit (120, 220, 420, 520, 620) and the second power transistor (114) is a low-side transistor of the bridge circuit (120, 220, 420, 520, 620). [7] Method according to any one of claims 1-6, further comprising: Performing the second measurement (152, 252A, 252B) less than 100 microseconds within the time it takes to perform the first measurement (150, 250A, 250B). [8] Method according to any one of claims 1-7, further comprising: Performing the first measurement (150, 250A, 250B) and the second measurement (152, 252A, 252B) during the freewheeling phase (301A, 301B) of a single switching cycle of the bridge circuit (120, 220, 420, 520, 620). [9] The method of claim 8, further comprising one or more of: Performing the first measurement (150, 250A, 250B) before the second measurement (152, 252A, 252B) during the switching cycle; and Performing the second measurement (152, 252A, 252B) before the first measurement (150, 250A, 250B) during the switching cycle. [10] Method according to any one of claims 1-9, wherein performing the first measurement (150, 250A, 250B) comprises measuring a voltage drop across drain and source terminals of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3) and the second measurement (152, 252A, 252B) comprises measuring a voltage drop across a body diode of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3). [11] Method according to any one of claims 1-10, further comprising: Using the junction temperature, determined based on the first measurement (150, 250A, 250B), to calculate an R DSON to determine the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3); and Using the second measurement (152, 252A, 252B) and the determined R DSON of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3) to determine a load current of the bridge circuit (120, 220, 420, 520, 620). [12] Controller configured to: Control of a bridge circuit (120, 220, 420, 520, 620) in a freewheeling phase in which a freewheeling current flows through a body diode of a power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3) of the bridge circuit (120, 220, 420, 520, 620); Performing an initial measurement (150, 250A, 250B) during the freewheeling phase (301A, 301B) to determine a junction temperature of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3); and Performing a second measurement (152, 252A, 252B) during the freewheeling phase (301A, 301B) to determine a drain voltage of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3). [13] Control according to claim 12, wherein the control is configured to: Performing the first measurement (150, 250A, 250B) during a passive part of the freewheeling phase (301A, 301B); and Performing the second measurement (152, 252A, 252B) during an active part of the freewheeling phase (301A, 301B). [14] Control according to one of claims 12 and 13, wherein the control is configured to: Performing the second measurement (152, 252A, 252B) less than 10 microseconds within the performance of the first measurement (150, 250A, 250B). [15] Control according to any one of claims 12-14, wherein the control is configured to: Performing the first measurement (150, 250A, 250B) and the second measurement (152, 252A, 252B) during the freewheeling phase (301A, 301B) of a single switching cycle of the bridge circuit (120, 220, 420, 520, 620). [16] Control according to any one of claims 12-15, wherein the control is configured to: Using the junction temperature, determined based on the first measurement (150, 250A, 250B), to calculate an R DSONto determine the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3); and Using the second measurement (152, 252A, 252B) and the determined R DSON of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3) to determine a load current of the bridge circuit (120, 220, 420, 520, 620). [17] System, encompassing: a motor (140, 240); a bridge circuit (120, 220, 420, 520, 620) that is controllable to supply energy to the motor (140, 240); and a controller (160) that is configured to: Operating a bridge circuit (120, 220, 420, 520, 620) in a freewheeling phase (301A, 301B) in which a freewheeling current flows through a body diode of a power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3) of the bridge circuit; Performing an initial measurement (150, 250A, 250B) during the freewheeling phase (301A, 301B) to determine a junction temperature of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3); and Performing a second measurement (152, 252A, 252B) during the freewheeling phase (301A, 301B) to determine a drain voltage of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3). [18] System according to claim 17, wherein the controller (160) is configured to: Performing the first measurement (150, 250A, 250B) during a passive part of the freewheeling phase (301A, 301B); and Performing the second measurement (152, 252A, 252B) during an active part of the freewheeling phase (301A, 301B). [19] System according to one of claims 17 and 18, wherein the controller (160) is configured to: Performing the first measurement (150, 250A, 250B) and the second measurement (152, 252A, 252B) during the freewheeling phase (301A, 301B) of a single switching cycle of the bridge circuit (120, 220, 420, 520, 620). [20] System according to one of claims 17-19, wherein the controller (160) is configured to: Using the junction temperature, determined based on the first measurement (150, 250A, 250B), to calculate an R DSON to determine the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3); and Using the second measurement (152, 252A, 252B) and the determined R DSON of the power transistor (112, 114, HS1-HS3, LS1-LS3, H1-H3, L1-L3) to determine a load current of the bridge circuit (120, 220, 420, 520, 620).

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