Dual-resistor motor control circuit and motor control system

Abstract

The present disclosure provides a double-resistance motor control circuit and a motor control system. The double-resistance motor control circuit comprises a main controller, a first phase current sampling circuit, a second phase current sampling circuit and a third phase current sampling circuit, the first phase current sampling circuit, the second phase current sampling circuit and the third phase current sampling circuit each comprise N power conversion units, each power conversion unit is electrically connected with the same phase winding of a different motor, a first sampling resistor is arranged in the first phase current sampling circuit to collect the first phase current of N motors, a second sampling resistor is arranged in the second phase current sampling circuit to collect the second phase current of N motors, the main controller is used to obtain the corresponding third phase current based on the first phase current and the second phase current of each motor, and control the operating state of each motor based on the first phase current, the second phase current and the third phase current; wherein N is a positive integer greater than 1. The double-resistance sampling of the present disclosure can reduce the cost.

Description

Technical Field

[0001] This disclosure relates to the field of electric motors, and in particular to a dual-resistance motor control circuit and a motor control system. Background Technology

[0002] With economic development and social progress, range hoods, refrigerators, and air conditioners have gradually become indispensable household appliances in people's daily lives. Variable frequency drive fans generally use permanent magnet synchronous motors (PMSMs). With technological advancements, two PMSMs are sometimes used in a single appliance. A single microcontroller (MCU) is used to control these two PMSMs. In practical applications, there are situations where two PMSMs operate simultaneously. However, MCUs often lack an AD (analog-to-digital) sampling unit, and under high-power operation, the sampling resistor is costly and occupies circuit board space.

[0003] Using Hall effect sensors to sample the phase current of a motor is simple, but the cost is high. To reduce costs, three resistors are connected in series in the lower arm circuit of a three-phase inverter for sampling. However, if two permanent magnet synchronous motors are running at the same time and share the three resistors for sampling, there will be overlap in the sampling points of the two motor phase currents, which will make it impossible to sample.

[0004] Therefore, when driving two permanent magnet synchronous motors simultaneously, the generation method and sampling strategy of the PWM (pulse width modulation) of the two sets of six inverters are technical problems that the industry needs to solve. Summary of the Invention

[0005] The technical problem to be solved by this disclosure is to overcome the shortcomings of the prior art, such as high cost of motor phase current sampling and inability to simultaneously collect multiple motor phase currents, and to provide a dual-resistance motor control circuit and motor control system.

[0006] This disclosure solves the above-mentioned technical problems through the following technical solution:

[0007] According to a first aspect of this disclosure, a dual-resistance motor control circuit is provided, the dual-resistance motor control circuit including a main controller, a first-phase current sampling circuit, a second-phase current sampling circuit and a third-phase current sampling circuit;

[0008] The first phase current sampling circuit, the second phase current sampling circuit, and the third phase current sampling circuit each include N power conversion units. The first end of each power conversion unit is electrically connected to the main controller, and the second end of each power conversion unit is electrically connected to the same phase winding of different motors.

[0009] Each of the power conversion units includes a drive circuit, an upper bridge arm circuit and a lower bridge arm circuit electrically connected to the drive circuit, the connection point of the upper bridge arm circuit and the lower bridge arm circuit is the second terminal, and one second terminal corresponds to one phase winding of the motor;

[0010] In the first phase current sampling circuit, the lower bridge arm circuit of each power conversion unit and the main controller are electrically connected to the third terminal of the first sampling resistor, and the fourth terminal of the first sampling resistor is grounded.

[0011] In the second phase current sampling circuit, the lower bridge arm circuit of each power conversion unit and the main controller are electrically connected to the fifth terminal of the second sampling resistor, and the sixth terminal of the second sampling resistor is grounded.

[0012] The first phase current sampling circuit is used to collect the first phase current of N motors based on sampling instructions, and transmit the first phase current to the main controller;

[0013] The second phase current sampling circuit is used to collect the second phase current of N motors based on the sampling command, and transmit the second phase current to the main controller;

[0014] The main controller is used to obtain the corresponding third phase current based on the first phase current and the second phase current of each motor, and to control the operating state of each motor based on the first phase current, the second phase current and the third phase current;

[0015] Where N is a positive integer greater than 1.

[0016] Preferably, the first phase current sampling circuit further includes a first current amplification unit, and the second phase current sampling circuit further includes a second current amplification unit;

[0017] The third terminal of the first sampling resistor is electrically connected to the main controller via the first current amplification unit;

[0018] The first current amplification unit is used to amplify the input first phase current and transmit the amplified first phase current to the main controller.

[0019] The fifth terminal of the second sampling resistor is electrically connected to the main controller via the second current amplification unit;

[0020] The second current amplification unit is used to amplify the input second phase current and transmit the amplified second phase current to the main controller.

[0021] Preferably, when N=2;

[0022] The two power conversion units in the first phase current sampling circuit are a first power conversion unit and a second power conversion unit, respectively.

[0023] The two power conversion units in the second phase current sampling circuit are the third power conversion unit and the fourth power conversion unit, respectively;

[0024] The main controller is used to control the closed state of the first power conversion unit and the second power conversion unit to collect the first phase current of the first motor or the second motor.

[0025] The main controller is also used to control the closed state of the third power conversion unit and the fourth power conversion unit to collect the second phase current of the first motor or the second motor.

[0026] Preferably, the main controller includes a signal generator;

[0027] The signal generator is used to generate a PWM wave to control each motor based on the instructions of the main controller, and transmits it to the corresponding motor via the first phase current sampling circuit, the second phase current sampling circuit and the third phase current sampling circuit to control the operating state of each motor.

[0028] Preferably, the main controller further includes a timer, and the signal generator includes a triangular wave generator;

[0029] The triangular wave generator is used to generate the PWM wave that controls each of the motors;

[0030] The timer is used to measure the period of the PWM wave;

[0031] The main controller is used to determine the sampling time of the first motor and the second motor based on the period of the PWM wave, and generate the sampling command at the sampling time.

[0032] Preferably, the main controller is used to control the triangular wave generator to generate a first PWM wave for controlling the first motor and a second PWM wave for controlling the second motor;

[0033] The first power conversion unit includes a first upper bridge arm circuit and a first lower bridge arm circuit;

[0034] The second power conversion unit includes a second upper bridge arm circuit and a second lower bridge arm circuit;

[0035] The third power conversion unit includes a third upper bridge arm circuit and a third lower bridge arm circuit;

[0036] The fourth power conversion unit includes a fourth upper bridge arm circuit and a fourth lower bridge arm circuit;

[0037] The main controller is also used to insert a first preset voltage vector into the first PWM wave and a second preset voltage vector into the second PWM wave at the first sampling time, and control the first upper bridge arm circuit, the second lower bridge arm circuit, the third upper bridge arm circuit, and the fourth lower bridge arm circuit to be disconnected, and the first lower bridge arm circuit, the second upper bridge arm circuit, the third lower bridge arm circuit, and the fourth upper bridge arm circuit to be closed, so as to collect the first phase current and the second phase current of the first motor;

[0038] Wherein, the first sampling time is the overflow time or underflow time of the first PWM wave.

[0039] Preferably, the main controller is further configured to insert a third preset voltage vector into the first PWM wave and a fourth preset voltage vector into the second PWM wave at the second sampling time, and control the first lower bridge arm circuit, the second upper bridge arm circuit, the third lower bridge arm circuit, and the fourth upper bridge arm circuit to be disconnected, and the first upper bridge arm circuit, the second lower bridge arm circuit, the third upper bridge arm circuit, and the fourth lower bridge arm circuit to be closed, so as to collect the first phase current and the second phase current of the second motor;

[0040] Wherein, when the first sampling time is the overflow time, the second sampling time is the underflow time of the second PWM wave; when the first sampling time is the underflow time, the second sampling time is the overflow time of the second PWM wave.

[0041] Preferably, the duration of the preset voltage vector is equal to the duration of the sampling window;

[0042] And / or,

[0043] The main controller is used to obtain the corresponding third-phase current based on the following formula:

[0044]

[0045] in, The third phase current, The first phase current, This is the second phase current.

[0046] Preferably, the triangular wave generator generates the PWM wave that controls each of the motors, satisfying the following condition:

[0047]

[0048] Among them, Dmax T represents the maximum duty cycle corresponding to the PWM wave signal. pwm The signal period of the PWM wave is T, and the duration of the sampling window is T.

[0049] According to a second aspect of this disclosure, a motor control system is provided, the motor control system comprising N motors and the dual-resistance motor control circuit described in the first aspect of this disclosure.

[0050] Based on common knowledge in the field, the preferred conditions described can be combined arbitrarily to obtain the preferred embodiments of this disclosure.

[0051] The positive improvements of this disclosure are as follows: By short-circuiting the lower bridge arm circuits of N power conversion units and connecting them in series with a sampling resistor grounded, the sampling resistor is shared to collect the phase current corresponding to N permanent magnet synchronous motors, reducing the number of sampling resistors and lowering costs. A single microcontroller can simultaneously control two motors, sampling the phase current of both motors within one PWM cycle and controlling both sets of inverters simultaneously, resulting in high real-time performance. Furthermore, by sharing a triangular wave generator, the microcontroller only needs one timer interrupt to achieve simultaneous control of the two motors, reducing the requirements on the microcontroller. The low-cost dual-resistor sampling scheme, using a shared sampling resistor, further reduces costs. Attached Figure Description

[0052] Figure 1 This is the first circuit diagram of the dual-resistance motor control circuit in Example 1;

[0053] Figure 2 This is the second circuit diagram of the dual-resistance motor control circuit in Example 1;

[0054] Figure 3 This is the third circuit diagram of the dual-resistance motor control circuit in Example 1;

[0055] Figure 4 This is the fourth circuit diagram of the dual-resistance motor control circuit in Example 1;

[0056] Figure 5 This is the fifth circuit diagram of the dual-resistance motor control circuit in Example 1;

[0057] Figure 6 This is the sixth circuit diagram of the dual-resistance motor control circuit in Example 1;

[0058] Figure 7 The output strategy and phase current sampling time diagram of the power conversion unit SVPWM (Space Vector Pulse Width Modulation) in Example 1 are shown below;

[0059] Figure 8 This is a diagram showing the closed state of the power conversion unit at the first sampling moment in Example 1.

[0060] Figure 9 This is a diagram showing the closed state of the power conversion unit at the second sampling moment in Example 1;

[0061] Figure 10 This is a schematic diagram of the voltage vector and sector in Example 1;

[0062] Figure 11 Here is the control flowchart of the main controller in Example 1;

[0063] Figure 12 This is a circuit diagram of the motor control system in Example 2. Detailed Implementation

[0064] The present disclosure is further illustrated below by way of embodiments, but the present disclosure is not limited to the scope of the embodiments described herein.

[0065] Example 1

[0066] In one specific embodiment of this disclosure, a dual-resistance motor control circuit 100 is provided, such as... Figure 1-2 As shown, the dual-resistance motor control circuit 100 includes a main controller 1, a first-phase current sampling circuit 2, a second-phase current sampling circuit 3, and a third-phase current sampling circuit 4.

[0067] The first phase current sampling circuit 2, the second phase current sampling circuit 3, and the third phase current sampling circuit 4 each include N power conversion units 11. The first end 111 of each power conversion unit 11 is electrically connected to the main controller 1, and the second end 112 of each power conversion unit 11 is electrically connected to the same phase winding of different motors.

[0068] Each power conversion unit 11 includes a drive circuit 113, an upper bridge arm circuit 114 and a lower bridge arm circuit 115 electrically connected to the drive circuit 113, and the connection point between the upper bridge arm circuit 114 and the lower bridge arm circuit 115 is a second terminal 112, and one second terminal 112 corresponds to one phase winding of a motor.

[0069] In the first phase current sampling circuit 2, the lower bridge arm circuit 115 of each power conversion unit 11 and the main controller 1 are electrically connected to the third terminal of the first sampling resistor 21, and the fourth terminal of the first sampling resistor 21 is grounded.

[0070] In the second phase current sampling circuit 3, the lower bridge arm circuit 115 of each power conversion unit 11 and the main controller 1 are electrically connected to the fifth terminal of the second sampling resistor 31, and the sixth terminal of the second sampling resistor 31 is grounded.

[0071] The first phase current sampling circuit 2 is used to collect the first phase current of N motors based on the sampling command, and transmit the first phase current to the main controller 1;

[0072] The second-phase current sampling circuit 3 is used to collect the second-phase current of N motors based on the sampling command and transmit the second-phase current to the main controller 1.

[0073] The main controller 1 is used to obtain the corresponding third phase current based on the first phase current and the second phase current of each motor, and to control the operating status of each motor based on the first phase current, the second phase current and the third phase current;

[0074] Where N is a positive integer greater than 1.

[0075] Specifically, in the dual-resistance motor control circuit 100, the first-phase current sampling circuit 2, the second-phase current sampling circuit 3, and the third-phase current sampling circuit 4 are all electrically connected to the first-phase winding, the second-phase winding, and the third-phase winding of the N motors respectively through N power conversion units 11. That is, the second terminals 112 of the N power conversion units 11 in the first-phase current sampling circuit 2 are electrically connected to the first-phase windings of the N motors respectively, the second terminals 112 of the N power conversion units 11 in the second-phase current sampling circuit 3 are electrically connected to the second-phase windings of the N motors respectively, and the second terminals 112 of the N power conversion units 11 in the third-phase current sampling circuit 4 are electrically connected to the third-phase windings of the N motors respectively. Each power conversion unit 11 is connected to the main controller 1. The first-phase winding, the second-phase winding, and the third-phase winding correspond to the U-phase, V-phase, and W-phase of the motor, respectively.

[0076] For the first phase current sampling circuit 2 and the second phase current sampling circuit 3, when the drive circuit 113 receives the sampling command from the main controller, it controls the closing state of the upper bridge arm circuit 114 and the lower bridge arm circuit 115 in the N power conversion units 11 of the first phase current sampling circuit 2 and the second phase current sampling circuit 3, thereby collecting the first phase current and the second phase current of N motors.

[0077] Among them, such as Figure 3 As shown, the upper bridge arm circuit 114 and lower bridge arm circuit 115 of each power conversion unit 11 can be IGBT (Insulated Gate Bipolar Transistor). The emitters of the lower bridge arm circuits 115 of N power conversion units 11 are shorted. The drive circuit 113 can be a pre-drive chip. The power conversion unit 11 takes the PWM complementary signal of the main controller 1 as input, the pre-drive chip and the upper and lower power switches IGBT as inverters, and the common terminal of the upper and lower power switches IGBT as output, which is connected to one phase winding of the motor.

[0078] Since the first phase current sampling circuit 2 and the second phase current sampling circuit 3 are equipped with sampling resistors, they can sample the phase current. Therefore, the first phase current sampling circuit 2 and the second phase current sampling circuit 3 can collect the two-phase current in each motor. After obtaining the two-phase current in each motor, the main controller 1 can reconstruct the third phase current based on the principle that the vector sum of the three-phase currents is zero. Then, it performs motor drive control calculations based on the U-phase current, V-phase current and W-phase current of each motor, generates PWM complementary signals, and controls the operating state of each motor.

[0079] For example, the N power conversion units 11 in the first phase current sampling circuit 2 are connected to the U-phase windings of the N motors respectively to collect the U-phase current of the N motors. The N power conversion units 11 in the second phase current sampling circuit 3 are connected to the V-phase windings of the N motors respectively to collect the V-phase current of the N motors. The N power conversion units 11 in the third phase current sampling circuit 4 are connected to the W-phase windings of the N motors respectively. Each power conversion unit 11 is connected to only one phase winding of one motor. The main controller 1 collects the U-phase current and V-phase current corresponding to each motor through the first phase current sampling circuit 2 and the second phase current sampling circuit 3, reconstructs the corresponding W-phase current, performs drive control calculations for each motor, and thus realizes the control of the operating state of each motor.

[0080] The motor can be a permanent magnet synchronous motor.

[0081] It should be noted that, Figure 2 and Figure 3 Taking the circuit diagram of the first phase current sampling circuit 2 as an example, after the emitters of the lower bridge arm circuit 115 of the N power conversion units 11 are short-circuited, the first sampling resistor 21 is connected in series. The circuit diagrams of the second phase current sampling circuit 3 and the third phase current sampling circuit 4 are not shown, but can be referred to in conjunction with... Figure 1 and Figure 2 To understand.

[0082] This specific implementation method achieves the acquisition of one-phase current corresponding to N motors using only one sampling resistor by shorting the lower bridge arm circuits of N power conversion units and connecting them in series with a sampling resistor to ground. This reduces the number of sampling resistors, lowers costs, saves circuit board space, and enables high-quality, refined processes. It utilizes two sampling resistors to simultaneously sample the phase current of N motors within one PWM cycle and uses one main controller to simultaneously control N motors. By controlling N sets of inverters simultaneously, it achieves high real-time performance.

[0083] In one specific embodiment, the first phase current sampling circuit 2 further includes a first current amplification unit, and the second phase current sampling circuit 3 further includes a second current amplification unit.

[0084] The third terminal of the first sampling resistor 21 is electrically connected to the main controller 1 via the first current amplification unit;

[0085] The first current amplification unit is used to amplify the input first phase current and transmit the amplified first phase current to the main controller 1.

[0086] The fifth terminal of the second sampling resistor 31 is electrically connected to the main controller 1 via the second current amplification unit;

[0087] The second current amplification unit is used to amplify the input second phase current and transmit the amplified second phase current to the main controller 1.

[0088] Specifically, taking the first phase current sampling circuit 2 as an example, such as Figure 4 As shown, in order to ensure that the phase current received by the main controller is within the preset output current range and to improve the signal-to-noise ratio of the current, the first phase current sampling circuit 2 is further equipped with a first current amplification unit 22, which is electrically connected to the first sampling resistor 21 and the main controller 1 respectively, to amplify the acquired phase current and transmit the amplified phase current to the main controller. The second phase current sampling circuit 3 is similar.

[0089] In one specific implementation, such as Figure 5 As shown, when N=2;

[0090] The two power conversion units 11 in the first phase current sampling circuit 2 are the first power conversion unit 211 and the second power conversion unit 212, respectively.

[0091] The two power conversion units 11 in the second phase current sampling circuit 3 are the third power conversion unit 311 and the fourth power conversion unit 312, respectively.

[0092] The main controller 1 is used to control the closed state of the first power conversion unit 211 and the second power conversion unit 212 to collect the first phase current of the first motor or the second motor.

[0093] The main controller 1 is also used to control the closed state of the third power conversion unit 311 and the fourth power conversion unit 312 to collect the second phase current of the first motor or the second motor.

[0094] Specifically, for dual-motor control (i.e., N=2), the first-phase current sampling circuit 2, the second-phase current sampling circuit 3, and the third-phase current sampling circuit 4 are electrically connected to the three-phase windings of the two motors, respectively. For example, the first power conversion unit 211 in the first-phase current sampling circuit 2 is electrically connected to the first-phase winding of the first motor, the second power conversion unit 212 is electrically connected to the first-phase winding of the second motor, the third power conversion unit 311 in the second-phase current sampling circuit 3 is electrically connected to the second-phase winding of the first motor, the fourth power conversion unit 312 is electrically connected to the second-phase winding of the second motor, and the two power conversion units in the third-phase current sampling circuit 4 are electrically connected to the third-phase windings of the first motor and the second motor, respectively.

[0095] When collecting the phase currents of the first motor and the second motor, the main controller 1 controls the closed state of the first power conversion unit 211, the second power conversion unit 212, the third power conversion unit 311, and the fourth power conversion unit 312 to collect the first phase current and the second phase current of the first motor and the second motor. Then, based on the principle that the vector sum of the three phase currents is zero, the third phase current is reconstructed to obtain the three phase currents corresponding to the first motor and the second motor.

[0096] In one specific embodiment, the main controller 1 includes a signal generator;

[0097] The signal generator is used to generate PWM waves to control each motor based on the instructions of the main controller 1. The PWM waves are transmitted to the corresponding motors via the first phase current sampling circuit 2, the second phase current sampling circuit 3 and the third phase current sampling circuit 4 to control the operating state of each motor.

[0098] In one specific embodiment, the main controller 1 further includes a timer, and the signal generator includes a triangular wave generator;

[0099] A triangular wave generator is used to generate PWM waves to control each motor;

[0100] The timer is used to measure the period of the PWM wave;

[0101] The main controller 1 is used to determine the sampling time of the first motor and the second motor based on the period of the PWM wave, and to generate sampling instructions at the sampling time.

[0102] Specifically, the first phase current sampling circuit 2, the second phase current sampling circuit 3, and the third phase current sampling circuit 4 use the same triangular carrier signal to generate a PWM wave. The timer determines the sampling time of the first motor and the second motor by measuring the period of the PWM wave generated by the triangular carrier signal, and generates a sampling command when the sampling time is reached to control the closing state of the first power conversion unit 211, the second power conversion unit 212, the third power conversion unit 311, and the fourth power conversion unit 312, thereby obtaining the three-phase currents corresponding to the first motor and the second motor.

[0103] This specific implementation uses a shared triangular wave generator, so the main controller 1 only needs one timer interrupt to achieve simultaneous control of two motors. It has low requirements for the microcontroller and adopts a low-cost dual-resistor sampling scheme, sharing the sampling resistor, which further reduces costs.

[0104] In one specific implementation, the main controller 1 is used to control the triangular wave generator to generate a first PWM wave for controlling the first motor and a second PWM wave for controlling the second motor;

[0105] like Figure 6 As shown, the first power conversion unit 211 includes a first upper bridge arm circuit 2111 and a first lower bridge arm circuit 2112;

[0106] The second power conversion unit 212 includes a second upper bridge arm circuit 2121 and a second lower bridge arm circuit 2122;

[0107] The third power conversion unit 311 includes a third upper bridge arm circuit 3111 and a third lower bridge arm circuit 3112;

[0108] The fourth power conversion unit 312 includes a fourth upper bridge arm circuit 3121 and a fourth lower bridge arm circuit 3122;

[0109] The main controller 1 is also used to insert a first preset voltage vector V into the first PWM wave at the first sampling time. 00X Insert a second preset voltage vector V into the second PWM wave 11Y And control the first upper bridge arm circuit 2111, the second lower bridge arm circuit 2122, the third upper bridge arm circuit 3111, and the fourth lower bridge arm circuit 3122 to disconnect, and the first lower bridge arm circuit 2112, the second upper bridge arm circuit 2121, the third lower bridge arm circuit 3112, and the fourth upper bridge arm circuit 3121 to close, so as to collect the first phase current and the second phase current of the first motor;

[0110] Wherein, the first sampling time is the overflow time or underflow time of the first PWM wave.

[0111] Specifically, the underflow time (start time) or overflow time (intermediate time) of the triangular carrier signal wave can be used as the sampling time of the phase current of the first motor, that is, the underflow time or overflow time of the triangular carrier signal is the first sampling time.

[0112] At the first sampling moment, the main controller 1 inserts a first preset voltage vector V into the first PWM wave. 00X Insert a second preset voltage vector V into the second PWM wave 11Y It controls the upper bridge arm of the first power conversion unit 211 and the third power conversion unit 311, which are electrically connected to the first phase winding and the second phase winding of the first motor, to open and the lower bridge arm to close. It also controls the upper bridge arm of the second power conversion unit 212 and the fourth power conversion unit 312, which are electrically connected to the first phase winding and the second phase winding of the second motor, to close and the lower bridge arm to open, thereby realizing the acquisition of the first phase current and the second phase current of the first motor.

[0113] That is, such as Figure 7-8 As shown, at the first sampling time, a first preset voltage vector V is inserted into the first PWM wave. 00X Insert a second preset voltage vector V into the second PWM wave 11Y The system controls the first upper bridge arm circuit 2111 to open, the first lower bridge arm circuit 2112 to close, the second upper bridge arm circuit 2121 to close, and the second lower bridge arm circuit 2122 to open in order to collect the first phase current of the first motor; and controls the third upper bridge arm circuit 3111 to open, the third lower bridge arm circuit 3112 to close, the fourth upper bridge arm circuit 3121 to close, and the fourth lower bridge arm circuit 3122 to open in order to collect the second phase current of the first motor.

[0114] It should be noted that V 00X and V 11Y For a pre-defined voltage vector, where V 00X Low level, V 11Y When the first sampling time arrives, a sampling time is artificially constructed by inserting a low-level voltage vector into the first PWM wave controlling the first motor, so as to achieve sampling of the phase current of the first motor. At the same time, by inserting a high-level voltage vector into the second PWM wave controlling the second motor, the influence of the second motor on the phase current sampling of the first motor is avoided, thus ensuring the reliability and accuracy of the phase current sampling of the first motor.

[0115] In one specific embodiment, the main controller 1 is further configured to insert a third preset voltage vector V into the first PWM wave at the second sampling time. 11X Insert a fourth preset voltage vector V into the second PWM wave. 00YAnd control the first lower bridge arm circuit 2112, the second upper bridge arm circuit 2121, the third lower bridge arm circuit 3112, and the fourth upper bridge arm circuit 3121 to disconnect, and the first upper bridge arm circuit 2111, the second lower bridge arm circuit 2122, the third upper bridge arm circuit 3111, and the fourth lower bridge arm circuit 3122 to close, so as to collect the first phase current and the second phase current of the second motor;

[0116] Wherein, when the first sampling time is the overflow time, the second sampling time is the underflow time of the second PWM wave; when the first sampling time is the underflow time, the second sampling time is the overflow time of the second PWM wave.

[0117] Specifically, the underflow or overflow time of the triangular carrier signal can be used as the sampling time of the phase current of the second motor, that is, the underflow or overflow time of the triangular carrier signal is the second sampling time. If the first sampling time is an underflow time, the overflow time can be used as the second sampling time; conversely, if the first sampling time is an overflow time, the underflow time can be used as the second sampling time.

[0118] At the second sampling time, the main controller 1 inserts a third preset voltage vector V into the first PWM wave. 11X Insert a fourth preset voltage vector V into the second PWM wave. 00Y It controls the upper bridge arm of the first power conversion unit 211 and the third power conversion unit 311, which are electrically connected to the first phase winding and the second phase winding of the first motor, to close and the lower bridge arm to open. It also controls the upper bridge arm of the second power conversion unit 212 and the fourth power conversion unit 312, which are electrically connected to the first phase winding and the second phase winding of the second motor, to open and the lower bridge arm to close, thereby realizing the acquisition of the first phase current and the second phase current of the second motor.

[0119] That is, such as Figure 7 and Figure 9 As shown, at the second sampling time, a third preset voltage vector V is inserted into the first PWM wave. 11X Insert a fourth preset voltage vector V into the second PWM wave. 00Y It controls the first upper bridge arm circuit 2111 to close, the first lower bridge arm circuit 2112 to open, the second upper bridge arm circuit 2121 to open, and the second lower bridge arm circuit 2122 to close in order to collect the first phase current of the second motor; it controls the third upper bridge arm circuit 3111 to close, the third lower bridge arm circuit 3112 to open, the fourth upper bridge arm circuit 3121 to open, and the fourth lower bridge arm circuit 3122 to close in order to collect the second phase current of the second motor.

[0120] Where V 11X and V 00Y For a pre-set voltage vector, V 11X Low level, V00Y It is a high level.

[0121] This specific implementation utilizes a time-division voltage vector insertion strategy. By inserting a high level, the unsampled motor does not affect the sampling of the phase current of the sampled motor. This enables the sampling of the phase current of two motors within one PWM cycle, avoiding timing conflicts in phase current sampling when two permanent magnet synchronous motors are working simultaneously and sharing a dual-resistor sampling circuit.

[0122] In one specific implementation, the duration of the preset voltage vector is equal to the duration of the sampling window;

[0123] Specifically, since the preset voltage vector is a manually constructed sampling time, phase current sampling is performed within the duration of the preset voltage vector insertion. That is, the duration of the preset voltage vector is equal to the sampling window duration. For example, the sampling window duration T∈[1,3]us, or T=2us. The specific sampling window duration can be adjusted as needed; this implementation does not impose specific limitations.

[0124] In one specific implementation, the main controller 1 is used to obtain the corresponding third-phase current based on the following formula:

[0125]

[0126] in, The third phase current, The first phase current, This is the second phase current.

[0127] Specifically, such as Figure 10 As shown, the voltage space vector of a three-phase motor can typically be divided into six sectors. Based on the principle that the vector sum of the three-phase currents is zero, after acquiring the first-phase current and the second-phase current of the first motor, it is possible to... The third-phase current of the first motor is reconstructed. Similarly, the corresponding third-phase current of the second motor can be reconstructed from the first-phase and second-phase currents.

[0128] In one specific implementation, the triangular wave generator produces a PWM wave that controls each motor while satisfying the following conditions:

[0129]

[0130] Among them, D max T represents the maximum duty cycle corresponding to the PWM wave signal. pwm T represents the signal period of the PWM wave, and T is the duration of the sampling window.

[0131] Specifically, since a preset voltage vector with the same duration as the sampling window needs to be inserted into the PWM wave, the maximum duty cycle of the PWM wave signal needs to be adjusted to allow for the insertion time of the preset voltage vector, so as to realize the insertion of the preset voltage vector, perform phase current acquisition, and ensure that the phase current sampling between the first motor and the second motor does not interfere with each other.

[0132] In a specific example, such as Figure 11 As shown, the underflow time of the triangular carrier signal is taken as the first sampling time, and the overflow time of the triangular carrier signal is taken as the second sampling time. The control process of the main controller 1 is as follows:

[0133] Step 1: The permanent magnet synchronous motor starts. The first phase current sampling circuit 2, the second phase current sampling circuit 3, and the third phase current sampling circuit 4 use the same triangular carrier signal to generate SVPWM waves, and both motors run.

[0134] Step 2: Determine if the triangular carrier signal is underflowing. If yes, proceed to step 3; otherwise, proceed to step 4.

[0135] Step 3: Insert voltage vector V into the SVPWM wave corresponding to the first motor. 00X A voltage vector V is inserted into the SVPWM wave corresponding to the second motor. 11Y The insertion time is the sampling window time T, and the phase current of the first motor is collected;

[0136] Step 4: Determine if the triangular carrier signal is overflowing. If so, proceed to step 5; otherwise, return to step 2.

[0137] Step 5: Insert voltage vector V into the SVPWM wave corresponding to the first motor. 11X A voltage vector V is inserted into the SVPWM wave corresponding to the second motor. 00Y The insertion time is the sampling window time T, and the phase current of the second motor is collected.

[0138] Step 6: By sampling the current, the U-phase current of the first motor and the second motor can be obtained. and V-phase current Wherein, the W-phase current is

[0139] Select the corresponding power conversion unit, generate an SVPWM wave, control the motor corresponding to the sampled current, and return to step 2; where the maximum duty cycle D of the SVPWM modulated PWM signal is... max satisfy

[0140]

[0141] T pwmThe period corresponding to the PWM signal is generally T. pwm ∈[50,250]us, or, T pwm =100us.

[0142] This embodiment reduces the number of sampling resistors and lowers costs by shorting the lower bridge arm circuits of N power conversion units and connecting them in series with a sampling resistor grounded. The shared sampling resistor is used to collect the phase current of one phase corresponding to N permanent magnet synchronous motors. A single microcontroller simultaneously controls two motors, sampling the phase current of both motors within one PWM cycle and controlling both inverters simultaneously, resulting in high real-time performance. Furthermore, by sharing a triangular wave generator, the microcontroller only needs one timer interrupt to achieve simultaneous control of the two motors, reducing the requirements on the microcontroller. The low-cost dual-resistor sampling scheme, using a shared sampling resistor, further reduces costs.

[0143] Example 2

[0144] In one specific embodiment of this disclosure, a motor control system is provided, such as... Figure 12 As shown, the motor control system includes N motors 200 and the dual-resistance motor control circuit 100 of Embodiment 1. The specific implementation principle can be found in Embodiment 1, and will not be repeated here.

[0145] This motor control system can be used in various electrical appliances such as floor scrubbers, dishwashers with drain pumps, refrigerators with dual compressors, and range hoods with dual fan systems.

[0146] This embodiment reduces the number of sampling resistors and lowers costs by shorting the lower bridge arm circuits of N power conversion units and connecting them in series with a sampling resistor grounded. The shared sampling resistor is used to collect the phase current of one phase corresponding to N permanent magnet synchronous motors. A single microcontroller simultaneously controls two motors, sampling the phase current of both motors within one PWM cycle and controlling both inverters simultaneously, resulting in high real-time performance. Furthermore, by sharing a triangular wave generator, the microcontroller only needs one timer interrupt to achieve simultaneous control of the two motors, reducing the requirements on the microcontroller. The low-cost dual-resistor sampling scheme, using a shared sampling resistor, further reduces costs.

[0147] While specific embodiments of this disclosure have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this disclosure is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this disclosure, but all such changes and modifications fall within the scope of protection of this disclosure.

Claims

1. A dual-resistance motor control circuit, characterized in that, The dual-resistance motor control circuit includes a main controller, a first-phase current sampling circuit, a second-phase current sampling circuit, and a third-phase current sampling circuit. The first phase current sampling circuit, the second phase current sampling circuit, and the third phase current sampling circuit each include N power conversion units. The first end of each power conversion unit is electrically connected to the main controller, and the second end of each power conversion unit is electrically connected to the same phase winding of different motors. Each of the power conversion units includes a drive circuit, an upper bridge arm circuit and a lower bridge arm circuit electrically connected to the drive circuit, the connection point of the upper bridge arm circuit and the lower bridge arm circuit is the second terminal, and one second terminal corresponds to one phase winding of the motor; In the first phase current sampling circuit, the lower bridge arm circuit of each power conversion unit and the main controller are electrically connected to the third terminal of the first sampling resistor, and the fourth terminal of the first sampling resistor is grounded. In the second phase current sampling circuit, the lower bridge arm circuit of each power conversion unit and the main controller are electrically connected to the fifth terminal of the second sampling resistor, and the sixth terminal of the second sampling resistor is grounded. The first phase current sampling circuit is used to collect the first phase current of N motors based on sampling instructions, and transmit the first phase current to the main controller; The second phase current sampling circuit is used to collect the second phase current of N motors based on the sampling command, and transmit the second phase current to the main controller; The main controller is used to obtain the corresponding third phase current based on the first phase current and the second phase current of each motor, and to control the operating state of each motor based on the first phase current, the second phase current and the third phase current; Where N is a positive integer greater than 1.

2. The dual-resistance motor control circuit according to claim 1, characterized in that, The first phase current sampling circuit further includes a first current amplification unit, and the second phase current sampling circuit further includes a second current amplification unit; The third terminal of the first sampling resistor is electrically connected to the main controller via the first current amplification unit; The first current amplification unit is used to amplify the input first phase current and transmit the amplified first phase current to the main controller. The fifth terminal of the second sampling resistor is electrically connected to the main controller via the second current amplification unit; The second current amplification unit is used to amplify the input second phase current and transmit the amplified second phase current to the main controller.

3. The dual-resistance motor control circuit according to claim 1, characterized in that, When N=2; The two power conversion units in the first phase current sampling circuit are a first power conversion unit and a second power conversion unit, respectively. The two power conversion units in the second phase current sampling circuit are the third power conversion unit and the fourth power conversion unit, respectively; The main controller is used to control the closed state of the first power conversion unit and the second power conversion unit to collect the first phase current of the first motor or the second motor. The main controller is also used to control the closed state of the third power conversion unit and the fourth power conversion unit to collect the second phase current of the first motor or the second motor.

4. The dual-resistance motor control circuit according to claim 3, characterized in that, The main controller includes a signal generator; The signal generator is used to generate a PWM wave to control each motor based on the instructions of the main controller, and transmits it to the corresponding motor via the first phase current sampling circuit, the second phase current sampling circuit and the third phase current sampling circuit to control the operating state of each motor.

5. The dual-resistance motor control circuit according to claim 4, characterized in that, The main controller also includes a timer, and the signal generator includes a triangular wave generator; The triangular wave generator is used to generate the PWM wave that controls each of the motors; The timer is used to measure the period of the PWM wave; The main controller is used to determine the sampling time of the first motor and the second motor based on the period of the PWM wave, and generate the sampling command at the sampling time.

6. The dual-resistance motor control circuit according to claim 5, characterized in that, The main controller is used to control the triangular wave generator to generate a first PWM wave to control the first motor and a second PWM wave to control the second motor. The first power conversion unit includes a first upper bridge arm circuit and a first lower bridge arm circuit; The second power conversion unit includes a second upper bridge arm circuit and a second lower bridge arm circuit; The third power conversion unit includes a third upper bridge arm circuit and a third lower bridge arm circuit; The fourth power conversion unit includes a fourth upper bridge arm circuit and a fourth lower bridge arm circuit; The main controller is also used to insert a first preset voltage vector into the first PWM wave and a second preset voltage vector into the second PWM wave at the first sampling time, and control the first upper bridge arm circuit, the second lower bridge arm circuit, the third upper bridge arm circuit, and the fourth lower bridge arm circuit to be disconnected, and the first lower bridge arm circuit, the second upper bridge arm circuit, the third lower bridge arm circuit, and the fourth upper bridge arm circuit to be closed, so as to collect the first phase current and the second phase current of the first motor; Wherein, the first sampling time is the overflow time or underflow time of the first PWM wave.

7. The dual-resistance motor control circuit according to claim 6, characterized in that, The main controller is also used to insert a third preset voltage vector into the first PWM wave and a fourth preset voltage vector into the second PWM wave at the second sampling time, and control the first lower bridge arm circuit, the second upper bridge arm circuit, the third lower bridge arm circuit, and the fourth upper bridge arm circuit to be disconnected, and the first upper bridge arm circuit, the second lower bridge arm circuit, the third upper bridge arm circuit, and the fourth lower bridge arm circuit to be closed, so as to collect the first phase current and the second phase current of the second motor; Wherein, when the first sampling time is the overflow time, the second sampling time is the underflow time of the second PWM wave; when the first sampling time is the underflow time, the second sampling time is the overflow time of the second PWM wave.

8. The dual-resistance motor control circuit according to claim 7, characterized in that, The duration of the preset voltage vector is equal to the duration of the sampling window; And / or, The main controller is used to obtain the corresponding third-phase current based on the following formula: in, The third phase current, The first phase current, This is the second phase current.

9. The dual-resistance motor control circuit according to claim 8, characterized in that, The triangular wave generator produces a PWM wave that controls each of the motors, satisfying the following condition: Among them, D max T represents the maximum duty cycle corresponding to the PWM wave signal. pwm The signal period of the PWM wave is T, and the duration of the sampling window is T.

10. A motor control system, characterized in that, The motor control system includes N motors and a dual-resistance motor control circuit as described in any one of claims 1 to 9.

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