Motor current measurement device and method

Abstract

Embodiments of the present disclosure relate to motor current measurement apparatuses and methods. An apparatus comprising: a first inverter configured to drive a first motor having a plurality of phases; the first inverter comprising a plurality of inverter legs, each inverter leg coupled to a corresponding phase of the first motor; a second inverter configured to drive a second motor having a plurality of phases, the second inverter comprising a plurality of inverter legs, each inverter leg coupled to a corresponding phase of the second motor; and a first current sensor configured to sense current flowing in the first inverter and the second inverter, wherein the first current sensor is shared by at least two inverter legs.

Description

Technical Field

[0001] This disclosure generally relates to current measurement devices and methods in multi-inverter and multi-motor systems. Background Technology

[0002] The motor requires three-phase AC current to establish a first magnetic field in the stator. This first magnetic field rotates at a speed synchronized with the AC power applied to the stator windings. The first magnetic field induces a current in the rotor of the AC motor. This induced current establishes a second magnetic field in the rotor. The rotor's second magnetic field reacts with the stator's first magnetic field. The interaction between the first and second magnetic fields generates a mechanical torque that pulls the rotor into rotation.

[0003] In a three-phase AC motor system, the AC motor comprises three-phase windings. These three-phase windings can be configured in two different ways: WYE configuration and Delta configuration. During operation, the power supply is available in direct current (DC) form. A three-phase inverter can be used to convert DC power to AC power.

[0004] The three-phase inverter comprises three inverter branches, each including two switches connected in series. The common node of the two switches in the first branch is connected to the first phase winding of the three-phase AC motor. The common node of the two switches in the second branch is connected to the second phase winding of the three-phase AC motor. The common node of the two switches in the third branch is connected to the third phase winding of the three-phase AC motor.

[0005] In operation, pulse width modulation (PWM) signals are used to control the switching on / off of the three-phase inverter. Specifically, the rotation of the three-phase AC motor is controlled by controlling the switching on / off of the three-phase inverter. The speed and torque of the three-phase AC motor can be adjusted by using PWM signals to control the amplitude and frequency of the three-phase output voltage generated by the three-phase inverter.

[0006] To better control the operation of a three-phase AC motor, it is necessary to accurately measure the current flowing through each phase winding. The current flowing through each phase winding can be measured using a current-sensing resistor connected in series with the phase winding. The voltage drop across the resistor is used to determine the current flowing through the phase winding. A three-phase AC motor may require three current-sensing resistors to accurately measure the current flowing through all three windings.

[0007] To simplify current measurement, at least one current sensing resistor can be removed based on the fact that the sum of all three currents flowing through the three phases of a three-phase AC motor is equal to zero, and the current of the phase without a current sensing resistor can be calculated based on the current of the two phases with current sensing resistors.

[0008] The aforementioned current measurement techniques require at least two current sensing devices (e.g., current-sensing resistors) in each three-phase AC motor. In multi-inverter and multi-motor systems (e.g., dual-inverter and dual-motor systems), a large number of current sensing devices are used to achieve accurate current measurement. A large number of current sensing devices can occupy additional space, increase circuit complexity and the total cost of the bill of materials, and lead to unnecessary power losses. There is a need for simple and cost-effective current sensing devices and methods to accurately measure the current flowing through multi-inverter and multi-motor systems. Summary of the Invention

[0009] According to an embodiment, an apparatus includes: a first inverter configured to drive a first motor having multiple phases, the first inverter including multiple inverter branches, each inverter branch coupled to a corresponding phase of the first motor; a second inverter configured to drive a second motor having multiple phases, the second inverter including multiple inverter branches, each inverter branch coupled to a corresponding phase of the second motor; and a first current sensor configured to sense current flowing in the first inverter and the second inverter, wherein the first current sensor is shared by at least two inverter branches.

[0010] According to another embodiment, a method includes: configuring a first inverter to drive a first motor, wherein the first inverter includes a plurality of inverter branches, each inverter branch coupled to a corresponding phase of the first motor; configuring a second inverter to drive a second motor, wherein the second inverter includes a plurality of inverter branches, each inverter branch coupled to a corresponding phase of the second motor; and connecting a first current sensor in series with at least two inverter branches. The at least two inverter branches originate from two different inverters.

[0011] According to another embodiment, a system includes: a first inverter having a plurality of inverter branches, each inverter branch including two switches connected in series; a first motor having a plurality of phases, each phase configured to be driven by a corresponding inverter branch of the first inverter; a second inverter having a plurality of inverter branches, each inverter branch including two switches connected in series; a second motor having a plurality of phases, each phase configured to be driven by a corresponding inverter branch of the second inverter; and a current sensing device configured to sense current flowing in the first inverter and the second inverter, wherein the current sensing device is shared by at least two inverter branches.

[0012] The features and technical advantages of this disclosure have been outlined rather broadly above, which will allow for a better understanding of the detailed description that follows. Additional features and advantages of this disclosure, which form the subject matter of the claims, will be described below. Those skilled in the art will understand that the disclosed concepts and specific embodiments can be readily used as the basis for modifying or designing other structures or processes to achieve the same purpose as this disclosure. Those skilled in the art will also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure as set forth in the appended claims. Attached Figure Description

[0013] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, wherein:

[0014] Figure 1 The figure illustrates a block diagram of a dual-motor system in a first current sensing configuration according to various embodiments of the present disclosure;

[0015] Figure 2 Various embodiments according to this disclosure are illustrated. Figure 1 A schematic diagram of the dual-motor system is shown in the image;

[0016] Figure 3 The illustration shows the PWM mode of a dual-motor system under a first current sensing configuration according to various embodiments of the present disclosure;

[0017] Figure 4 The figure illustrates a block diagram of a dual-motor system in a second current sensing configuration according to various embodiments of the present disclosure;

[0018] Figure 5 Various embodiments according to this disclosure are illustrated. Figure 4 The diagram shown is of a dual-motor system.

[0019] Figure 6 The illustration shows a first PWM mode of a dual-motor system in a second current sensing configuration according to various embodiments of the present disclosure;

[0020] Figure 7 The illustration shows a second PWM mode of a dual-motor system in a second current sensing configuration according to various embodiments of the present disclosure;

[0021] Figure 8 The figure illustrates a third PWM mode of a dual-motor system in a second current sensing configuration according to various embodiments of the present disclosure;

[0022] Figure 9 The illustration shows a fourth PWM mode of a dual-motor system in a second current sensing configuration according to various embodiments of the present disclosure;

[0023] Figure 10The figure illustrates a fifth PWM mode of a dual-motor system in a second current sensing configuration according to various embodiments of the present disclosure;

[0024] Figure 11 The illustration shows a sixth PWM mode of a dual-motor system in a second current sensing configuration according to various embodiments of the present disclosure;

[0025] Figure 12 The illustration shows a seventh PWM mode of a dual-motor system in a second current sensing configuration according to various embodiments of the present disclosure;

[0026] Figure 13 The illustration shows an eighth PWM mode of a dual-motor system in a second current-sensing configuration according to various embodiments of the present disclosure; and

[0027] Figure 14 The illustration shows a flowchart of a method for detecting current in a dual-motor system according to various embodiments of the present disclosure.

[0028] Unless otherwise specified, corresponding numbers and symbols in different figures generally refer to corresponding parts. The figures are drawn to clearly illustrate relevant aspects of the various embodiments and are not necessarily drawn to scale. Detailed Implementation

[0029] The following describes in detail the making and use of embodiments of the present invention. However, it should be understood that the concepts disclosed herein can be embodied in a wide variety of specific contexts, and the specific embodiments discussed herein are illustrative only and not intended to limit the scope of the claims. Furthermore, it should be understood that various changes, substitutions, and modifications can be made without departing from the spirit and scope of this disclosure as defined by the appended claims.

[0030] This invention will be described in the context of preferred embodiments, specifically current measurement devices and methods in multi-inverter and multi-motor systems. However, the invention is also applicable to various motor drive applications. For example, the method can be applied to permanent magnet synchronous motors (PMSMs) where a rotor magnetic field is generated by a magnet. The method can also be applied to switched reluctance motors and synchronous reluctance motors operating on the principle of achieving minimum energy and / or reluctance configuration. In the following, various embodiments will be explained in detail with reference to the accompanying drawings.

[0031] Figure 1 A block diagram of a dual-motor system under a first current sensing configuration according to various embodiments of the present disclosure is illustrated. The dual-motor system includes a first motor 111, a first inverter 101, a second motor 112, a second inverter 102, a first current sensor S1, a second current sensor S2, and a third current sensor S3. Figure 1As shown, the first inverter 101 and the second inverter 102 are connected in parallel, and are also connected in series with current sensors S1-S3 between the first voltage bus VIN+ and the second voltage bus VIN-. In some embodiments, the first voltage bus VIN+ may be coupled to the output of the DC power supply. The second voltage bus VIN- may be coupled to ground.

[0032] The first motor 111 includes multiple phases. The first inverter 101 includes multiple inverter branches. Each of the multiple inverter branches of the first inverter 101 is coupled to a corresponding phase of the first motor 111. The first inverter 101 is configured to drive the first motor 111. In some embodiments, the first motor 111 includes three phases. The first motor 111 is a three-phase AC motor. The first inverter 101 includes three inverter branches. Each of the three inverter branches of the first inverter 101 is coupled to a corresponding phase of the first motor 111. Detailed structures of the first motor 111 and the first inverter 101 will be described in reference to... Figure 2 This will be described in detail below.

[0033] The second motor 112 includes multiple phases. The second inverter 102 includes multiple inverter branches. Each of the multiple inverter branches of the second inverter 102 is coupled to a corresponding phase of the second motor 112. The second inverter 102 is configured to drive the second motor 112. In some embodiments, the second motor 112 includes three phases. The second motor 112 is a three-phase AC motor. The second inverter 102 includes three inverter branches. Each of the three inverter branches of the second inverter 102 is coupled to a corresponding phase of the second motor 112. Detailed structures of the second motor 112 and the second inverter 102 will be described in reference to... Figure 2 This will be described in detail below.

[0034] like Figure 1 As shown, a first current sensor S1 is coupled to a first inverter 101 and a second inverter 102. Specifically, the first inverter branch of the first inverter 101 and the first inverter branch of the second inverter 102 are connected in parallel and are also connected in series with the first current sensor S1. The first current sensor S1 is configured to sense the current flowing through the first inverter branch of the first inverter 101 and the first inverter branch of the second inverter 102 in an alternating manner. The detailed operating principle of the first current sensor S1 will be explained in [reference needed]. Figure 3 This will be described in detail below.

[0035] like Figure 1As shown, the second current sensor S2 is coupled to the first inverter 101 and the second inverter 102. Specifically, the second inverter branch of the first inverter 101 and the second inverter branch of the second inverter 102 are connected in parallel and are also connected in series with the second current sensor S2. The second current sensor S2 is configured to sense the current flowing through the second inverter branch of the first inverter 101 and the second inverter branch of the second inverter 102 in an alternating manner. The detailed operating principle of the second current sensor S2 will be explained in [reference needed]. Figure 3 This will be described in detail below.

[0036] like Figure 1 As shown, the third current sensor S3 is coupled to the first inverter 101 and the second inverter 102. Specifically, the third inverter branch of the first inverter 101 and the third inverter branch of the second inverter 102 are connected in parallel, and are also connected in series with the third current sensor S3. The third current sensor S3 is configured to sense the current flowing through the third inverter branch of the first inverter 101 and the third inverter branch of the second inverter 102 in an alternating manner. The detailed operating principle of the third current sensor S3 will be explained in [reference needed]. Figure 3 This will be described in detail below.

[0037] In some embodiments, Figure 1 The current sensor shown (e.g., S1) can be implemented as a current-sensing resistor or multiple current-sensing resistors connected in parallel. In an alternative embodiment, Figure 1 The current sensor shown (e.g., S1) can be implemented as an isolated current sensor, such as a Hall effect current sensor.

[0038] In operation, a controller (not shown) can be used to process the detected current of the dual-motor system. The controller can be implemented as a microcontroller unit (MCU), digital signal processor (DSP), etc. During current measurement, the controller can continuously decode all phase currents of the two motors separately by synchronizing the current sampling process with the applied PWM signal.

[0039] It should be noted that multiple associated circuits can be set between the current sensor and the controller. These associated circuits include operational amplifiers, regulation networks, filters, etc.

[0040] It should also be noted that, Figure 1 Only two motors are shown in the motor system, which may include multiple such motors and an associated inverter. Figure 1The number of motors shown is limited only for the purpose of clearly illustrating the inventive aspects of various embodiments. The invention is not limited to any particular number of motors. For example, the current sensing technology described throughout the description can be applied to multiple motors (e.g., a three-motor system) or multiple generators (e.g., a three-generator system). Furthermore, the current sensing technology described throughout the description can be applied to multiphase motors (e.g., a six-phase motor).

[0041] It should also be noted that Figure 1 The current sensors S1, S2, and S3 shown are positioned below inverters 101 and 102. Those skilled in the art will understand that... Figure 1 The arrangement of the current sensors shown is merely an example. Those skilled in the art will recognize many variations, substitutions, and modifications. For instance, current sensors S1, S2, and S3 could be placed between the inverter and the first voltage bus VIN+.

[0042] Figure 2 Various embodiments according to this disclosure are illustrated. Figure 1 A schematic diagram of a dual-motor system is shown in the image. Figure 2 As shown, the first motor 111 includes three windings L11, L12, and L13. In some embodiments, the three windings L11, L12, and L13 are connected in a WYE configuration. Figure 2 As shown, the first ends of the three windings L11, L12, and L13 are connected together to form a neutral point. The second ends of the three windings L11, L12, and L13 are respectively connected to the inverter branches of the first inverter 101. The sum of the currents flowing into the neutral point is approximately zero. In some embodiments, the neutral point may be grounded. Throughout the description, L11 may also be referred to as the first phase of the first motor 111. Similarly, L12 and L13 may be referred to as the second and third phases of the first motor 111, respectively.

[0043] like Figure 2 As shown, the second motor 112 includes three windings L21, L22, and L23. In some embodiments, the three windings L21, L22, and L23 are connected in a WYE configuration. Figure 2 As shown, the first ends of the three windings L21, L22, and L23 are connected together to form a neutral point. The second ends of the three windings L21, L22, and L23 are respectively connected to the inverter branches of the second inverter 102. The sum of the currents flowing into the neutral point is approximately zero. In some embodiments, the neutral point may be grounded. Throughout the description, L21 may also be referred to as the first phase of the second motor 112. Similarly, L22 and L23 may be referred to as the second and third phases of the second motor 112, respectively.

[0044] The first branch of the first inverter 101 includes two switches Q11 and Q12 connected in series. The common node of the two switches Q11 and Q12 is connected to the first phase L11 of the first motor 111. The second branch of the first inverter 101 includes two switches Q13 and Q14 connected in series. The common node of the two switches Q13 and Q14 is connected to the second phase L12 of the first motor 111. The third branch of the first inverter 101 includes two switches Q15 and Q16 connected in series. The common node of the two switches Q15 and Q16 is connected to the third phase L13 of the first motor 111.

[0045] The first branch of the second inverter 102 includes two switches Q21 and Q22 connected in series. The common node of the two switches Q21 and Q22 is connected to the first phase L21 of the second motor 112. The second branch of the second inverter 102 includes two switches Q23 and Q24 connected in series. The common node of the two switches Q23 and Q24 is connected to the second phase L22 of the second motor 112. The third branch of the second inverter 102 includes two switches Q25 and Q26 connected in series. The common node of the two switches Q25 and Q26 is connected to the third phase L13 of the second motor 112.

[0046] According to an embodiment, Figure 2 The switch can be an insulated gate bipolar transistor (IGBT) device. Alternatively, the switching element can be any controllable switch, such as a metal-oxide-semiconductor field-effect transistor (MOSFET) device, an integrated gate commutated thyristor (IGCT) device, a gate turn-off thyristor (GTO) device, a silicon controlled rectifier (SCR) device, a junction gate field-effect transistor (JFET) device, a MOS-controlled thyristor (MCT) device, a gallium nitride (GaN)-based power device, a silicon carbide (SiC)-based power device, etc.

[0047] like Figure 2 As shown, the first branch of the first inverter 101 and the first branch of the second inverter 102 are connected in parallel and are also connected in series with the first current sensor S1. The second branch of the first inverter 101 and the second branch of the second inverter 102 are connected in parallel and are also connected in series with the second current sensor S2. The third branch of the first inverter 101 and the third branch of the second inverter 102 are connected in parallel and are also connected in series with the third current sensor S3. Figure 2 Each current sensor shown (e.g., S1) is shared by two inverter branches. These two inverter branches come from two different motors.

[0048] An advantageous feature of having current sensors S1, S2, and S3 is that each current sensor is shared between the two motors. As a result, the cost and space occupied by the current sensors can be effectively halved compared to conventional current sensor configurations.

[0049] Figure 3 The PWM mode of a dual-motor system under a first current-sensing configuration according to various embodiments of the present disclosure is shown. Figure 3 There can be six rows. The first row (Q12_G) represents the gate drive signal for switch Q12. The second row (Q14_G) represents the gate drive signal for switch Q14. The third row (Q16_G) represents the gate drive signal for switch Q16. The fourth row (Q22_G) represents the gate drive signal for switch Q22. The fifth row (Q24_G) represents the gate drive signal for switch Q24. The sixth row (Q26_G) represents the gate drive signal for switch Q26.

[0050] like Figure 3 As shown, one PWM cycle of the first motor 111 is from t0 to t2. The gate drive signals of Q12, Q14, and Q16 are symmetrical about the dashed line at t1. One PWM cycle of the second motor 112 is from t1 to t3. The gate drive signals of Q22, Q24, and Q26 are symmetrical about the dashed line at t2. Figure 3 As shown, the drive signals of the first inverter 101 and the second inverter 102 have a 180-degree phase shift. It should be noted that the first current sensing configuration and its associated current sensing method can also be applied to systems where the drive signals of the first and second inverters do not have a 180-degree phase shift. In this case, current sensing accuracy can be achieved by employing an appropriate control algorithm, such as dynamically changing the sampling time in each PWM cycle. By dynamically changing the sampling time in each PWM cycle, the sampling time of the first motor can be set at the moment when the lower switch of the first motor is turned on and the upper switch of the second motor is turned on. Similarly, the sampling time of the second motor can be set at the moment when the lower switch of the second motor is turned on and the upper switch of the first motor is turned on.

[0051] like Figure 3As shown, at t1, switches Q12, Q14, and Q16 are turned on, as indicated by gate drive signals Q12_G, Q14_G, and Q16_G. The current of the first motor 111 recirculates on the lower side of the first inverter 101. In other words, at t1, the current of the first motor 111 flows through switches Q12, Q14, and Q16 and the current sensors S1, S2, and S3 connected to the corresponding switches. At t1, switches Q22, Q24, and Q26 are turned off, as indicated by gate drive signals Q22_G, Q24_G, and Q26_G. The current of the second motor 112 recirculates on the upper side of the second inverter 102. In other words, at t1, the current of the second motor 112 does not flow through switches Q22, Q24, and Q26 and the current sensors S1, S2, and S3. Thus, at t1, the current sensors S1, S2, and S3 are able to sample the current of the first motor 111. Similarly, at t2, the current of the second motor 112 recirculates under the second inverter 102. The current of the first motor 111 does not flow through switches Q12, Q14, and Q16, nor through current sensors S1, S2, and S3. Thus, at t2, current sensors S1, S2, and S3 are able to sample the current of the second motor 112.

[0052] In operation, the first current sensor S1 is configured to sense the current flowing through the first branch of the first inverter 101 at a first time t1. The current flowing through the first branch of the first inverter 101 is the current flowing through the first phase of the first motor 111. The first current sensor S1 is configured to sense the current flowing through the first branch of the second inverter 102 at a second time t2. The current flowing through the first branch of the second inverter 102 is the current flowing through the first phase of the second motor 112.

[0053] In operation, the second current sensor S2 is configured to sense the current flowing through the second branch of the first inverter 101 at a first time t1. The current flowing through the second branch of the first inverter 101 is the current flowing through the second phase of the first motor 111. The second current sensor S2 is also configured to sense the current flowing through the second branch of the second inverter 102 at a second time t2. The current flowing through the second branch of the second inverter 102 is the current flowing through the second phase of the second motor 112.

[0054] In operation, the third current sensor S3 is configured to sense the current flowing through the third branch of the first inverter 101 at a first time t1. The current flowing through the third branch of the first inverter 101 is the current flowing through the third phase of the first motor 111. The third current sensor S3 is also configured to sense the current flowing through the third branch of the second inverter 102 at a second time t2. The current flowing through the third branch of the second inverter 102 is the current flowing through the third phase of the second motor 112.

[0055] Figure 4 A block diagram of a dual-motor system under a second current sensing configuration according to various embodiments of the present disclosure is illustrated. Figure 4 The dual-motor system shown is similar to Figure 1 The dual-motor system shown shares a single current sensor between the two motors. Figure 4 As shown, the first inverter 101 is connected between VIN+ and the first current sensor S1. Similarly, the second inverter 102 is connected between VIN+ and the first current sensor S1. S1 is configured to sample the phase currents of both motors.

[0056] Figure 5 Various embodiments according to this disclosure are illustrated. Figure 4 The diagram shows a dual-motor system. Figure 5 The dual-motor system shown is similar to Figure 2 The dual-motor system shown has the first, second, and third branches of the first inverter and the first, second, and third branches of the second inverter connected in parallel and connected in series with the first current sensor S1.

[0057] Figure 6 The illustration shows a first PWM mode of a dual-motor system under a second current-sensing configuration according to various embodiments of the present disclosure. Figure 6 There can be six rows. The first row (Q12_G) represents the gate drive signal for switch Q12. The second row (Q14_G) represents the gate drive signal for switch Q14. The third row (Q16_G) represents the gate drive signal for switch Q16. The fourth row (Q22_G) represents the gate drive signal for switch Q22. The fifth row (Q24_G) represents the gate drive signal for switch Q24. The sixth row (Q26_G) represents the gate drive signal for switch Q26.

[0058] like Figure 6 As shown, one PWM cycle for the first motor 111 and the second motor 112 is from t0 to t9. At t8, the center of the drive signal of the first inverter 101 is aligned with the center of the drive signal of the second inverter 102. In other words, the drive signal of the first inverter 101 is in phase with the drive signal of the second inverter 102.

[0059] like Figure 6 As shown, the gate drive signals of the first inverter 101 and the second inverter 102 are symmetrical about the dashed line at t8. The operating principle of the current sensor S1 in the second half of the cycle is similar to its operating principle in the first half of the cycle. For simplicity, the operating principle of the current sensor in the first half of the cycle will be discussed in detail below.

[0060] During operation, during the first current sampling duration from t0 to t1, the current flowing through current sensor S1 is zero. During the second current sampling duration from t1 to t2, the current flowing through current sensor S1 (IS1) is equal to -Ic1. Based on the current flowing through current sensor S1, the controller (not shown) is able to determine the current (Ic1) flowing through the third phase of the first motor 111.

[0061] During the third current sampling duration, ranging from t2 to t3, the current flowing through current sensor S1 is equal to the sum of -Ib1 and -Ic1. Since the sum of Ia1, Ib1, and Ic1 is zero, the controller is able to calculate the value of Ia1. In other words, based on the current flowing through current sensor S1, the controller is able to determine the current (Ia1) flowing through the first phase of the first motor 111.

[0062] During the fourth current sampling duration, ranging from t3 to t4, the current flowing through the current sensor S1 is equal to the sum of Ia1 and -Ia2. Since the value of Ia1 has already been determined during the third current sampling duration, the controller is therefore able to calculate the value of Ia2. In other words, based on the current flowing through the current sensor S1, the controller is able to determine the current (Ia2) flowing through the first phase of the second motor 112.

[0063] During the fifth current sampling duration, ranging from t4 to t5, the current flowing through current sensor S1 is equal to the sum of Ia1 and Ic2. Since the value of Ic1 has already been determined during the third current sampling duration, the controller is therefore able to calculate the value of Ic2. In other words, based on the current flowing through current sensor S1, the controller is able to determine the current (Ic2) flowing through the third phase of the second motor 112.

[0064] During the sixth current sampling duration, ranging from t5 to t6, the current flowing through current sensor S1 is equal to the sum of -Ib1, -Ic1, -Ia2, -Ib2, and -Ic2. Since the sum of the phase currents in each motor is zero, the controller is therefore able to calculate the value of Ia1. In other words, based on the current flowing through current sensor S1, the controller is able to determine the current (Ia1) flowing through the first phase of the first motor 111.

[0065] It should be noted that both the third and sixth current sampling durations are used to detect the current (Ia1) flowing through the first phase of the first motor 111. The controller can determine Ia1 based on the average of these two measurements.

[0066] During the seventh current sampling duration, ranging from t6 to t7, the current flowing through current sensor S1 is equal to the sum of -Ia1, -Ib1, -Ic1, -Ia2, -Ib2, and -Ic2. Since the sum of the phase currents in each motor is zero, the current flowing through current sensor S1 is zero.

[0067] Table 1 shows the application of the above current detection method. Figure 6 The direct and indirect current measurement results obtained in the first PWM mode shown.

[0068]

[0069]

[0070] Table 1

[0071] As shown in Table 1, at least one phase current (e.g., Ia2 or Ic2) is indirectly detected based on the directly measured phase current. Furthermore, the controller can determine the value of the current (Ib1) flowing through the second phase of the first motor 111, since Ib1 is equal to the sum of -Ia1 and -Ic1. Similarly, the controller can determine the value of the current (Ib2) flowing through the second phase of the second motor 112, since Ib2 is equal to the sum of -Ia2 and -Ic2.

[0072] Figure 7 A second PWM mode of a dual-motor system in a second current-sensing configuration according to various embodiments of the present disclosure is shown. Figure 7 The second PWM mode shown is similar to Figure 6 The first PWM mode shown is different except that the gate drive signals for Q12 and Q26 are swapped. The current sensing method applied to the second PWM mode is similar to that described above. Figure 6 The current detection method applied to the first PWM mode will not be discussed here to avoid repetition.

[0073] Table 2 shows the application of the above current detection method. Figure 7 The direct and indirect current measurement results obtained in the second PWM mode shown are as follows.

[0074]

[0075]

[0076] Table 2

[0077] As shown in Table 2, at least one phase current (e.g., Ia2) is indirectly detected based on the directly measured phase current. Furthermore, the controller can determine the value of Ib1 because Ib1 is equal to the sum of -Ia1 and -Ic1. Similarly, the controller can determine the value of Ib2 because Ib2 is equal to the sum of -Ia2 and -Ic2.

[0078] It should be noted that IC2 is detected indirectly during the fifth current sampling duration. During the sixth current sampling duration, Ic2 is detected directly. The controller can determine Ic2 based on the average of these two measurements.

[0079] Figure 8 The illustration shows a third PWM mode of a dual-motor system under a second current sensing configuration according to various embodiments of the present disclosure. Figure 8 The third PWM mode shown is similar to Figure 7 The second PWM mode shown is different except that the gate drive signals for Q22 and Q26 are swapped. The current detection method applied to the third PWM mode is similar to that described above. Figure 6 The current detection method applied to the first PWM mode will not be discussed here to avoid repetition.

[0080] Table 3 shows the application of the above current detection method. Figure 8 The direct and indirect current measurement results obtained using the third PWM mode shown are illustrated.

[0081]

[0082]

[0083] Table 3

[0084] As shown in Table 3, at least one phase current (e.g., Ia1) is indirectly detected based on the directly measured phase current. Furthermore, the controller can determine the value of Ib1 because Ib1 is equal to the sum of -Ia1 and -Ic1. Similarly, the controller can determine the value of Ib2 because Ib2 is equal to the sum of -Ia2 and -Ic2.

[0085] It should be noted that Ia2 is detected indirectly during the fifth current sampling duration. During the sixth current sampling duration, Ia2 is detected directly. The controller can determine Ic2 based on the average of these two measurements.

[0086] Figure 9 The illustration shows a fourth PWM mode of a dual-motor system under a second current sensing configuration according to various embodiments of the present disclosure. Figure 9 The fourth PWM mode shown is similar to Figure 8The third PWM mode shown is different except that the gate drive signals for Q12 and Q22 are swapped. The current sensing method applied to the fourth PWM mode is similar to that described above. Figure 6 The current detection method applied to the first PWM mode will not be discussed here to avoid repetition.

[0087] Table 4 shows the application of the above current detection method. Figure 9 The direct and indirect current measurement results obtained in the fourth PWM mode shown are as follows.

[0088]

[0089]

[0090] Table 4

[0091] As shown in Table 4, at least one phase current (e.g., Ic2) is indirectly detected based on the directly measured phase current. Furthermore, the controller can determine the value of Ib1 because Ib1 is equal to the sum of -Ia1 and -Ic1. Similarly, the controller can determine the value of Ib2 because Ib2 is equal to the sum of -Ia2 and -Ic2.

[0092] It should be noted that Ia1 is detected indirectly during the fourth current sampling duration. During the sixth current sampling duration, Ia1 is detected directly. The controller can determine Ia1 based on the average of these two measurements.

[0093] Figure 10 A fifth PWM mode of a dual-motor system under a second current-sensing configuration according to various embodiments of the present disclosure is shown. Figure 10 The fifth PWM mode shown is similar to Figure 9 The fourth PWM mode shown is different except that the gate drive signals for Q14 and Q24 are swapped. The current sensing method applied to the fifth PWM mode is similar to that described above. Figure 6 The current detection method applied to the first PWM mode will not be discussed here to avoid repetition.

[0094] Table 5 shows the application of the above current detection method. Figure 10 The direct and indirect current measurement results obtained using the fifth PWM mode shown are as follows.

[0095]

[0096]

[0097] Table 5

[0098] As shown in Table 5, at least one phase current (e.g., Ic2) is indirectly detected based on the directly measured phase current. Furthermore, the controller can determine the value of Ib1 because Ib1 is equal to the sum of -Ia1 and -Ic1. Similarly, the controller can determine the value of Ib2 because Ib2 is equal to the sum of -Ia2 and -Ic2.

[0099] It should be noted that Ia1 is detected indirectly during the fifth current sampling duration. During the sixth current sampling duration, Ia1 is detected directly. The controller can determine Ia1 based on the average of these two measurements.

[0100] Figure 11 A sixth PWM mode of a dual-motor system in a second current-sensing configuration according to various embodiments of the present disclosure is shown. Figure 11 The sixth PWM mode shown is similar to Figure 10 The fifth PWM mode shown is different except that the gate drive signals for Q12 and Q22 are swapped. The current sensing method applied to the sixth PWM mode is similar to that applied to the above-mentioned... Figure 6 The current detection method for the first PWM mode is not discussed here to avoid repetition.

[0101] Table 6 shows the application of the above current detection method. Figure 11 The direct and indirect current measurement results obtained using the sixth PWM mode shown are as follows.

[0102]

[0103]

[0104] Table 6

[0105] As shown in Table 6, at least one phase current (e.g., Ic2) is indirectly detected based on the directly measured phase current. Furthermore, the controller can determine the value of Ib1 because Ib1 is equal to the sum of -Ia1 and -Ic1. Similarly, the controller can determine the value of Ib2 because Ib2 is equal to the sum of -Ia2 and -Ic2.

[0106] It should be noted that Ia2 is detected indirectly during the fourth current sampling duration. During the sixth current sampling duration, Ia2 is detected directly. The controller can determine Ia2 based on the average of these two measurements.

[0107] Figure 12 A seventh PWM mode of a dual-motor system under a second current sensing configuration according to various embodiments of the present disclosure is shown. Figure 12 The seventh PWM mode shown is similar to Figure 8The third PWM mode shown is different except that the gate drive signals for Q12 and Q24 are swapped. The current sensing method applied to the seventh PWM mode is similar to that described above. Figure 6 The current detection method applied to the first PWM mode will not be discussed here to avoid repetition.

[0108] Table 7 shows the application of the above current detection method. Figure 12 The direct and indirect current measurement results obtained using the seventh PWM mode are shown.

[0109]

[0110]

[0111] Table 7

[0112] As shown in Table 7, at least one phase current (e.g., Ia1) is indirectly detected based on the directly measured phase current. Furthermore, the controller can determine the value of Ib1 because Ib1 is equal to the sum of -Ia1 and -Ic1. Similarly, the controller can determine the value of Ib2 because Ib2 is equal to the sum of -Ia2 and -Ic2.

[0113] It should be noted that IC2 is detected indirectly during the third current sampling duration. During the fifth current sampling duration, IC2 is detected directly. The controller can determine IC2 based on the average of these two measurements.

[0114] Figure 13 An eighth PWM mode of a dual-motor system under a second current-sensing configuration according to various embodiments of the present disclosure is shown. Except that the gate drive signals for Q14 and Q22 are swapped, Figure 13 The eighth PWM mode shown is similar to Figure 10 The fifth PWM mode is shown in the diagram. The current sensing method applied to the eighth PWM mode is similar to that applied to the aforementioned... Figure 6 The current detection method for the first PWM mode is not discussed here to avoid repetition.

[0115] Table 8 shows the application of the above current detection method. Figure 13 The direct and indirect current measurement results obtained in the eighth PWM mode shown are as follows.

[0116]

[0117]

[0118] Table 8

[0119] As shown in Table 8, at least one phase current (e.g., Ic2) is indirectly detected based on the directly measured phase current. Furthermore, the controller can determine the value of Ib1 because Ib1 is equal to the sum of -Ia1 and -Ic1. Similarly, the controller can determine the value of Ib2 because Ib2 is equal to the sum of -Ia2 and -Ic2.

[0120] It should be noted that IC1 is directly detected during the second current sampling duration. IC1 is also directly detected during the fifth current sampling duration. The controller can determine IC1 based on the average of these two measurements.

[0121] Figure 14 A flowchart of a method for detecting current in a dual-motor system according to various embodiments of the present disclosure is shown. Figure 14 The flowchart shown is merely an example and should not unduly limit the scope of the claims. Those skilled in the art will recognize numerous variations, substitutions, and modifications. For example, additions, removals, substitutions, rearrangements, and repetitions may be made. Figure 14 The steps shown.

[0122] Return to reference Figure 1 and Figure 4 The dual-motor system includes a first inverter (e.g., inverter 101) having multiple inverter branches, a first motor (e.g., motor 111), a second inverter (e.g., inverter 102), and a second motor (e.g., inverter 101). Each inverter branch includes two switches connected in series. The first motor has multiple phases, each configured to be driven by a corresponding branch of the first inverter. The second inverter has multiple inverter branches, each including two switches connected in series. The second motor (e.g., motor 112) has multiple phases, each configured to be driven by a corresponding branch of the second inverter.

[0123] Return to reference Figure 1 The current sensing device includes three current sensors (e.g., current sensors S1, S2, and S3). The current sensing device is configured to sense the current flowing in the first and second inverters. Each current sensor of the current sensing device is shared by two inverter branches. These two inverter branches originate from two different inverters.

[0124] Return to reference Figure 4 The current sensing device includes a single current sensor (e.g., current sensor S1). The current sensing device is configured to sense the current flowing in the first inverter and the second inverter. The single current sensor of the current sensing device is shared by the inverter branches of the first motor and the second motor.

[0125] An advantageous feature of incorporating a current sensing device is that the bill of materials (BOM) cost can be halved compared to conventional implementations of current sensing devices in motor drive applications. Furthermore, the space occupied by the current sensing device is reduced, simplifying printed circuit board (PCB) design. Current sensing devices also reduce the number of pins on the controller (e.g., MCU). Consequently, a smaller MCU package can be used in response to the reduced pin count. Additionally, current sensing devices reduce overall power consumption within the current sensing device itself.

[0126] In operation, the following steps are used to detect the current flowing in the first motor and the second motor.

[0127] In step 1402, the first inverter is configured to drive the first motor. The first inverter includes multiple inverter branches, each inverter branch being coupled to a corresponding phase of the first motor.

[0128] In step 1404, the second inverter is configured to drive the second motor. The second inverter includes multiple inverter branches, each inverter branch being coupled to a corresponding phase of the second motor.

[0129] In step 1406, the first current sensor is connected in series with at least two inverter branches. The at least two inverter branches come from two different inverters.

[0130] The method further includes configuring a first current sensor to detect the current flowing through a first inverter branch of the first inverter and a first inverter branch of the second inverter; configuring a second current sensor to detect the current flowing through a second inverter branch of the first inverter and a second inverter branch of the second inverter; and configuring a third current sensor to detect the current flowing through a third inverter branch of the first inverter and a third inverter branch of the second inverter.

[0131] The method also includes configuring the gate drive signals of the first inverter and the second inverter such that a 180-degree phase shift occurs between the gate drive signals of the first inverter and the second inverter.

[0132] The method further includes configuring a first current sensor to detect the current flowing through the first inverter branch, the second inverter branch, and the third inverter branch of the first inverter, as well as the current flowing through the first inverter branch, the second inverter branch, and the third inverter branch of the second inverter.

[0133] The method also includes configuring the gate drive signal of the first inverter and the gate drive signal of the second inverter so that the gate drive signal of the first inverter is in phase with the gate drive signal of the second inverter.

[0134] The method also includes sampling the phase currents of the first motor and the second motor in a sequential manner, wherein at least one phase current is indirectly detected based on the phase current that is directly measured.

[0135] While embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made without departing from the spirit and scope of the present disclosure as defined by the appended claims.

[0136] Furthermore, the scope of this application is not limited to the specific embodiments of the processes, machines, manufactures, material compositions, components, methods, and steps described in the specification. Those skilled in the art will readily understand from this disclosure that existing or future processes, machines, manufactures, material compositions, components, methods, or steps can perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, components, methods, or steps within their scope.

Claims

1. An apparatus comprising: A first inverter is configured to drive a first motor having multiple phases. The first inverter includes multiple inverter branches, each of which is coupled to a corresponding phase of the first motor. A second inverter is configured to drive a second motor having multiple phases. The second inverter includes multiple inverter branches, each of which is coupled to a corresponding phase of the second motor. as well as A first current sensor is configured to sense the current flowing in a first inverter and a second inverter, wherein the first current sensor is shared by at least two inverter branches, wherein: The first inverter branch, the second inverter branch, the third inverter branch, the first inverter branch, the second inverter branch, and the third inverter branch of the first inverter are connected in parallel and are also connected in series with the first current sensor.

2. The apparatus according to claim 1, wherein: The center of the drive signal of the first inverter is aligned with the center of the drive signal of the second inverter.

3. The apparatus according to claim 1, wherein At least one phase current is indirectly detected based on a directly measured phase current.

4. A method comprising: A first inverter is configured to drive a first motor, wherein the first inverter includes a plurality of inverter branches, each of the inverter branches being coupled to a corresponding phase of the first motor; A second inverter is configured to drive a second motor, wherein the second inverter includes a plurality of inverter branches, each of which is coupled to a corresponding phase of the second motor; The first current sensor is connected in series with at least two inverter branches, wherein the at least two inverter branches come from two different inverters; The first current sensor is configured to detect the current flowing through the first inverter branch, the second inverter branch, and the third inverter branch of the first inverter. And the current flowing through the first inverter branch, the second inverter branch, and the third inverter branch of the second inverter, wherein: The first inverter branch, the second inverter branch, the third inverter branch, the first inverter branch, the second inverter branch, and the third inverter branch of the first inverter are connected in parallel and are also connected in series with the first current sensor.

5. The method according to claim 4, further comprising: Configure the gate drive signals of the first inverter and the second inverter such that the gate drive signals of the first inverter and the second inverter are in phase.

6. The method according to claim 4, further comprising: The phase currents of the first motor and the second motor are sampled sequentially, wherein at least one phase current is indirectly detected based on a directly measured phase current.

7. A system comprising: The first inverter has multiple inverter branches, each of which includes two switches connected in series. The first motor has multiple phases, each of which is configured to be driven by a corresponding inverter branch of the first inverter. The second inverter has multiple inverter branches, each of which includes two switches connected in series. The second motor has multiple phases, each of which is configured to be driven by a corresponding inverter branch of the second inverter. A current sensing device is configured to sense the current flowing in the first inverter and the second inverter, wherein the current sensing device is shared by at least two inverter branches. The current sensing device includes a current sensor, and wherein: The plurality of inverter branches of the first inverter and the plurality of inverter branches of the second inverter are connected in parallel and are also connected in series with the current sensor; and The drive signals of the first inverter and the second inverter are in phase.

8. The system according to claim 7, wherein: The current sensor is a resistor.

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