Current reconstruction method for sampling of double Hall current sensors of permanent magnet synchronous motor

Abstract

The invention discloses a current reconstruction method for sampling of double Hall current sensors of a permanent magnet synchronous motor, relates to a current reconstruction method, and aims to solve the problems that the cost and the capacity of a control system are increased and a peripheral circuit is more complicated due to the fact that three Hall current sensors need to be adopted for current sampling in a traditional method. The method comprises the following steps: step 1, installing a Hall current sensor H1 and a Hall current sensor H2; step 2, setting sampling moments of the Hall current sensor H1 and the Hall current sensor H2; 3, setting the minimum sampling time of the Hall current sensor H1 and the Hall current sensor H2; 4, current reconstruction is carried out according to the current values is1, is2 and i0 obtained by sampling of the Hall current sensor H1 and the Hall current sensor H2, and the current values of the A phase, the B phase and the C phase are obtained. The invention belongs to the technical field of common direct current bus type open winding permanent magnet synchronous motor control.

Description

Technical Field

[0001] The invention relates to a current reconstruction method, and belongs to the technical field of common direct current bus type open-winding permanent magnet synchronous motor control. Background Art

[0002] Compared with ordinary permanent magnet synchronous motors, common DC bus open-winding permanent magnet synchronous motors have the advantages of high power density, high efficiency, low hardware cost, high reliability and high durability, and have been widely studied in the fields of electric vehicles, aerospace, and ship propulsion. In high-performance AC motor drive systems, it is often necessary to perform closed-loop control of the voltage source PWM inverter to obtain high-precision three-phase sinusoidal current, thereby ensuring fast and accurate electromagnetic torque control.

[0003] A typical voltage source PWM inverter is equipped with at least two Hall current sensors to provide phase current feedback signals. However, due to the existence of zero-sequence circuits in open-winding permanent magnet synchronous motors with a common DC bus, the traditional method requires the use of three Hall current sensors for current sampling, which increases the cost and capacity of the control system and makes the peripheral circuit more complicated. At the same time, due to the accuracy of the sensor, the zero-sequence current sampling results may have bias and proportional errors, reducing the zero-sequence current suppression capability. Because the open-winding permanent magnet synchronous motor with a common DC bus has higher requirements for control accuracy, it has higher requirements for current information. The current reconstruction method of the traditional permanent magnet synchronous motor to obtain current information is not suitable for the open-winding permanent magnet synchronous motor with a common DC bus containing zero-sequence current.

[0004] In order to reduce the system hardware cost and system complexity, this method designs a phase current reconstruction technology for a common DC bus open-winding permanent magnet synchronous motor drive based on two Hall current sensors, which avoids complex modulation algorithms and is better suitable for low-cost applications. Summary of the invention

[0005] In order to solve the problem that the traditional method needs to use three Hall current sensors for current sampling, which increases the cost and capacity of the control system and makes the peripheral circuit more complicated, the present invention proposes a current reconstruction method for permanent magnet synchronous motor dual Hall current sensor sampling.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problem is: the steps of the present invention include:

[0007] Step 1: Install Hall current sensor H1 and Hall current sensor H2;

[0008] Step 2, setting the sampling time of the Hall current sensor H1 and the Hall current sensor H2;

[0009] Step 3, setting the minimum sampling time of the Hall current sensor H1 and the Hall current sensor H2;

[0010] Step 4: According to the current value i obtained by sampling of the Hall current sensor H1 and the Hall current sensor H2 s1 、i s2 , i0 to reconstruct the current and obtain the current values ​​of each phase of A, B, and C.

[0011] Furthermore, the installation method of the Hall current sensor in step 1 is as follows: the common DC bus open-winding permanent magnet synchronous motor is a dual inverter structure, and the left and right inverters are inverter 1 and inverter 2 respectively; the Hall current sensor H1 samples the upper bridge arm S of inverter 1 11 and S 13 The positive bus current and the lower bridge arm S of inverter 1 14 and S 16 The negative bus current, the Hall current sensor H2 is set at the sampling point of the three-phase winding of the motor, and samples the sum of the three-phase currents, that is, directly obtains three times the zero-sequence current in the zero-sequence current.

[0012] Furthermore, the expression of zero-sequence current is:

[0013]

[0014] In formula (1), i0 represents the zero-sequence current value in the zero-sequence circuit, i a 、i b 、i c They respectively represent the phase current values ​​of the three phases A, B, and C in the motor winding.

[0015] Furthermore, the relationship between the sampling time and PWM in step 2 is: the sampling time of the Hall current sensor H1 and the Hall current sensor H2 are respectively set at the peak and trough of the PWM carrier; define t s1 and t s2 is the sampling time of the Hall current sensor H1, and t0 is the sampling time of the Hall current sensor H2; where t s1 ,t s2 are the moments of PWM carrier wave peak and carrier wave valley respectively, t0 is the moment of PWM carrier wave peak, and the carrier wave peak and carrier wave valley are respectively located at the space voltage vector V generated by the two inverters 1 and 2. 77 、V 00 Combined action time.

[0016] Furthermore, in step 3, the minimum sampling time is greater than the sum of the current ringing time, the A / D digital-to-analog conversion time, the dead time and the delay time. The expression of the minimum sampling time is:

[0017] t min>t dead +t delay +t set +t adc (2)

[0018] In formula (2), t min Indicates the minimum sampling time, t dead Denotes the dead time, t delay Denotes the delay time, t set represents the current ringing time, t adc Indicates the A / D digital-to-analog conversion time;

[0019] The minimum action time of the voltage vector combination in the setting space is greater than or equal to the minimum sampling time, that is:

[0020] min(Tv ij )≥t min (3)

[0021] In formula (3), Tv ij is the minimum action time of the space voltage vector combination. ij A space voltage vector combination (i, j=1, 2...8) is generated for inverter 1 and inverter 2 respectively.

[0022] Furthermore, in step 4, at the peak moment of the carrier wave in a single PWM, the two Hall current sensors H1 and H2 are sampled simultaneously, and the peak moment of the carrier wave corresponds to the zero space voltage vector combination V 77 The positive bus current flows through the upper bridge arm S of inverter 1. 11 , S 13 , S 15 Flows into the three-phase winding of the motor and passes through the upper bridge arm S of inverter 2 21 , S 23 , S 25 Flow out of the three-phase winding of the motor and return to the DC bus terminal; the Hall current sensor H1 samples the switch device S 11 , S 13 According to Kirchhoff’s current law, S 11 , S 13 The positive bus current is switched by the switching device S 13 , S 15 After the current is split, it is injected into the two-phase windings B and C of the motor, then S 11 , S 13 The current value is the sum of the currents of phases B and C, and the sampling current value is i s1 ; then:

[0023] i s1 =i b +i c

[0024] i b and i c They are the phase current values ​​of phase B and phase C in the three-phase winding of the motor respectively;

[0025] Zero space voltage vector combination V 77 When the inverter 1 and the inverter 2 are in operation, the upper arm switch devices S 11 , S 13 , S 15 , S 21 , S 23 , S 25 All are turned on, and the positive bus current is shunted through the three upper bridge arms of inverter 1 and input into the three phases of motor winding A, B, and C; the Hall current sensor H2 samples the current between the six potentials a1, a2, b1, b2, c1, and c2 between the two inverters 1 and 2, that is, samples the three-phase winding current of the open-winding permanent magnet synchronous motor, and the sampled current value is the sum of the three-phase currents; there is a zero-sequence circuit in the open-winding permanent magnet synchronous motor with a common DC bus, and the zero-sequence current is sampled by the Hall current sensor H2 through the three-phase winding; the zero-sequence current value is one-third of the sum of the three-phase currents; the current value sampled by the Hall current sensor H2 is i0; then:

[0026] i o =(i a +i b +i c )

[0027] i0 is the zero-sequence current value, i a 、i b 、i c They are the current values ​​of the three phases A, B and C respectively;

[0028] According to the modulation relationship between the carrier and the PWM wave, at the carrier valley moment, the zero space voltage vector combination V 00 The bus current passes through the lower bridge arm S of inverter 1. 12 , S 14 , S 16 Flows into the three-phase winding of the motor and passes through the lower bridge arm S of inverter 2 22 , S 24 , S 26 Flow out of the three-phase winding of the motor and return to the DC bus terminal; the Hall current sensor H1 samples the switch device S 14 , S 16 According to Kirchhoff's current law, the bus current is divided and flows through S 16 Input motor C phase winding, then S 14 , S 16 The current value between is the C phase current value, and the sampling current value is i s2 ; then:

[0029] i s2=i c

[0030] i c is the phase current value of phase C;

[0031] The three-phase current information of the motor winding is obtained by reconstructing the sampled current values ​​of the Hall current sensors H1 and H2 at different times; the reconstruction expression is:

[0032]

[0033] i s1 is the sum of the currents of phases B and C, i s2 The current value obtained by sampling is the C phase current, i s1 Subtract i s2 is the current value of phase B; i0 is the sum of the three-phase current values ​​obtained by sampling, i0 minus i s1 is the A phase current value.

[0034] The beneficial effects of the present invention are as follows: the present invention utilizes the Hall current sensor H2 to directly sample the sum of the three-phase currents, thereby avoiding the accumulation of sampling errors caused by the zero-sequence current, and further reducing the speed and torque ripples caused by the zero-sequence current. Moreover, the method of using two Hall current sensors to sample the bus current between the inverter bridge arms and the sum of the three-phase currents has the advantages of low complexity of the peripheral circuit and low hardware cost compared to the traditional method of using three Hall current sensors to directly sample the currents of each phase of the motor. By setting the sampling time of the two Hall current sensors, complex modulation algorithms and phase shift operations are avoided, and the system control cost is reduced. The present invention sets the sampling time of the Hall current sensor, and sets the sampling time of the two Hall current sensors H1 and H2 at the carrier peak and carrier valley in a single PWM. It avoids complex blind spot compensation strategies, and does not have the periodic blind spots in traditional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the block diagram of closed-loop control system;

[0036] Figure 2 It is a schematic diagram of the topological structure of a dual inverter of a permanent magnet synchronous motor with open windings and a common DC bus;

[0037] Figure 3 This is a schematic diagram of the current sampling timing in PWM;

[0038] Figure 4 is the space voltage vector V 77 Schematic diagram of the flow direction of current during action;

[0039] Figure 5 is the space voltage vector V 00 Schematic diagram of the flow direction of current during action;

[0040] Figure 6 is the sampling current value i s1 、i s2 Schematic diagram;

[0041] Figure 7 is the reconstructed current value waveform;

[0042] Figure 8 It is the actual current value waveform;

[0043] Fig. 9 It is the waveform diagram of system torque and phase current when the motor changes load torque and load speed;

[0044] Fig.10 is the sampling window t min Schematic diagram of the modulation relationship with the motor frequency. DETAILED DESCRIPTION

[0045] Specific implementation method 1: A current reconstruction method for sampling a dual Hall current sensor of a permanent magnet synchronous motor, the specific steps include:

[0046] Step 1: This method uses two Hall current sensors, where Hall current sensor H1 samples the upper bridge arm S of inverter 1. 11 and S 13 The positive bus current and S 14 and S 16 The negative bus current, the Hall current sensor H2 is set between a1, b1, c1 of inverter 1 and a2, b2, c2 of inverter 2, that is, at the three-phase winding of the motor, and samples the sum of the three-phase currents, that is, directly obtains the three-phase winding current of the motor, which is three times the zero-sequence current. Figure 1 The red circles shown are the setting points of the Hall current sensors H1 and H2.

[0047] Step 2: Set the sampling time and sampling frequency of the two Hall current sensors. The Hall current sensor H1 performs two samplings in PWM, and the sampling time is set at the carrier peak time and the carrier valley time respectively. The sampling current value of the Hall current sensor H1 at the carrier peak time is i s According to the modulation relationship between the carrier and the PWM wave, the gate control signal of inverter 1 and inverter 2 at the peak of the carrier wave is (111), which controls the upper bridge arm switch device S of inverter 1 and inverter 2. 11 , S 13 , S 15 , S 21 , S 23 , S 25 All conduction, zero space vector voltage combination V 77The positive bus current value sampled by the Hall current sensor H1 is the switching device S 11 , S 13 Current value between.

[0048] The sampling current value of the Hall current sensor H1 at the carrier valley moment in PWM is i s2 According to the modulation relationship between the carrier and the PWM wave, the gate control signal of inverter 1 and inverter 2 is (000) at the carrier valley moment, which controls the lower bridge arm switch device S of inverter 1 and inverter 2. 12 , S 14 , S 16 , S 22 , S 24 , S 26 All conduction, zero space voltage vector combination V 00 Function: the bus current value sampled by the Hall current sensor H1 is the switching device S 14 , S 16 The current value between.

[0049] The sampling time of the Hall current sensor H2 is set at the carrier wave peak time in the PWM, and the sampling current value of the Hall current sensor H2 is i0. According to the modulation relationship between the carrier and the PWM wave, at the carrier wave peak time, the gate control signal of inverter 1 and inverter 2 is (111), which controls the upper bridge arm switch device S of inverter 1 and inverter 2. 11 , S 13 , S 15 , S 21 , S 23 , S 25 All are turned on, the three-phase windings A, B, and C of the motor have current input, and the zero space vector voltage combination V 77 Function: The sampling current value of the Hall current sensor H2 is the sum of the three-phase current values. Figure 3 As shown, the action time of the zero space voltage vector V7 generated by the inverter 1 is greater than the action time of the zero space voltage vector V7* generated by the inverter 2, that is, the upper bridge arm S of the inverter 1 11 , S 13 , S 15 The total conduction time is greater than the upper bridge arm S of inverter 2 21 , S 23 , S 25 Total conduction time. By controlling the gate signals of the two inverters to the left and right to adjust the action time of the zero space voltage vector, the zero-sequence voltage between the two inverters is not zero, and the zero-sequence voltage with the opposite polarity to the zero-sequence current is injected into the three-phase winding to offset the influence of the zero-sequence current.

[0050] Step 3: Set the minimum sampling time of the two Hall current sensors H1 and H2.

[0051] First, set the sampling window (minimum sampling time) to t min This method sets the sampling window to 5.5μs, t min The expression is:

[0052] t min =t dead +t delay +t set +t adc

[0053] t dead is the dead time, t delay is the IGBT turn-on and turn-off delay time, t adc is the digital-to-analog conversion time. set is the decay time of the current ringing.

[0054] To prevent the current from switching between the two bridge arms during the sampling time, the minimum action time of the space voltage vector combination in a single PWM cycle should be greater than the minimum sampling time. The space voltage vector combination action time is:

[0055] min(Tv ij )≥t min

[0056] TV ij is the minimum action time of the space voltage vector combination. ij A space voltage vector combination is generated for the two inverters respectively, (i, j=1, 2...8).

[0057] Sampling time t s1 It is set at the carrier wave peak moment in PWM, in the space voltage vector combination V 77 The space voltage vector combination V 77 Action time:

[0058] min(Tv 77 )≥t min

[0059] Sampling time t s2 It is set at the carrier valley moment in PWM, in the space voltage vector combination V 00 The space voltage vector combination V 00 Action time:

[0060] min(Tv 00 )≥t min

[0061] Step 4: Reconstruct the phase current according to the sampled current value.

[0062] Among them, Figure 1 As shown, the bus current and the sum of the three-phase current values ​​are obtained by sampling the Hall current sensors H1 and H2 respectively set on the DC bus and the three-phase winding, and the three-phase current i is obtained by current reconstruction. n (n = a, b, c), the feedback i is obtained through Clark transformation and Park transformation d 、i q , i0 value, where the reference current i0* minus i0 is used to obtain the zero-sequence voltage u0* through the PR controller. d *, i0* are both zero. The dq axis reference current i d * and i q * Subtract the feedback current i d and i q Get the error current Δi d and Δi q , the reference voltage u is obtained through the PI regulator d * and u q *.u d *、u q *Through the inverse Park transformation, the dq axis is transformed to the αβ0 axis. Using the SVPMW modulation strategy, the current passes through the input end of the open-winding permanent magnet synchronous motor dual inverter structure with a common DC bus. Inverter 1 and Inverter 2 are controlled by SVPWM. Each inverter can generate 8 voltage vectors, and the number of possible voltage vector combinations generated by the left and right inverters is 64. SVPMW controls the action time of the space voltage vector in a single PWM cycle and forms a rotating circular magnetic field in the motor winding according to the volt-second theorem to drive the motor to rotate.

[0063] like Figure 2 As shown in the figure, there are two inverters on the left and right. The two inverters 1 and 2 on the left and right have three bridge arms and six switching devices. The switching device of the upper bridge arm of inverter 1 is S 11 , S 13 , S 15 , the lower bridge arm switch device of inverter 1 is S 12 , S 14 , S 16 The upper arm switch device of inverter 2 is S 21 , S 23 , S 25 , the lower bridge arm switch device of inverter 2 is S 22 , S 24 , S 26 The switch device adopts 180° complementary conduction mode, and introduces dead time to prevent the upper and lower bridge arms from being turned on at the same time and causing the bridge arms to short-circuit.

[0064] like Figure 4As shown in the figure, the arrow direction is the current flow direction. The current sampled by the Hall current sensor H1 is S 11 , S 13 The current at the PWM point corresponds to the sampling time t s1 , the current sampled by the Hall current sensor H1 can be expressed as: i s1 =i b +i c

[0065] i s1 t s1 The sampling value of the Hall current sensor at the DC bus at the moment i b and i c They are the phase current values ​​of phase B and phase C in the three-phase winding of the motor respectively.

[0066] like Figure 5 As shown, the current sampled by the Hall current sensor H1 is S 14 , S 16 The arrow in the figure indicates the direction of current flow. The sampling time in PWM is t s2 , the current value sampled by the Hall current sensor H1 can be expressed as: i s2 =i c

[0067] i s2 is the sampling current value of the Hall current sensor at the DC bus at time t0, i c is the C phase current value.

[0068] The Hall current sensors H1 and H2 are used to sample the current at different times in PWM. The sampled current values ​​obtained contain different phase current information. The current values ​​of each phase can be reconstructed and expressed as:

[0069]

[0070] i0 is the sum of the three-phase current values, i a 、i b 、i c They are the current values ​​of the three phases A, B, and C. All phase current information in the open-winding permanent magnet synchronous motor with a common DC bus can be obtained through the above phase current reconstruction method, and the three-phase winding current of the motor stator is directly sampled, that is, the sum of the three-phase current values ​​is directly sampled, which avoids the error caused by the zero-sequence current in each phase current. The use of two Hall current sensors reduces the complexity of the system structure, reduces the system peripheral circuits and hardware equipment, saves costs, and reduces the current error caused by multiple sampling devices.

[0071] like Figure 6As shown in the figure, the rated speed of the motor is set to 500r / min, the rated load torque is 5N·m, and the motor works under rated conditions. The current values ​​sampled and output by the two Hall current sensors H1 and H2 are i s .i s The output includes the phase current i of B and C. b 、i c , the current envelope waveform sampled and output is equal to the actual phase current value. Figure 6 The upper and lower envelope waveforms are i b +i c and i c .

[0072] like Figure 7 and Figure 8 As shown in the figure, the Hall current sensor only samples the current twice in a single PWM, so the reconstructed phase current is a discrete value. From the two current waveforms, it can be seen that the error between the actual phase current value and the reconstructed phase current value is small, which verifies that this reconstruction method can accurately obtain the actual current.

[0073] like Fig. 9 As shown, the motor load speed changes and the phase current changes obtained by reconstruction. The load speed increases from 200r / min at 0.3 seconds and reaches 1000r / min at 0.52 seconds. As the motor speed increases, the phase current frequency also gradually increases. It can be proved that the present invention can effectively reconstruct the phase current at different speeds.

[0074] like Fig.10 As shown in the figure, the changes of the reconstructed phase current. The load torque starts to increase from 2N·m at 0.3s and reaches 6N·m at 0.55s. As the load torque increases, the amplitude of the reconstructed phase current gradually increases, proving that the system's continuous load torque output torque can effectively track the load torque.

[0075] By changing the motor load torque and motor load speed, it is verified that the reconstructed phase current obtained by this method is reliable under different load torques and load speeds.

[0076] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A current reconstruction method for sampling a dual Hall current sensor of a permanent magnet synchronous motor, characterized in that: The specific steps include Step 1: Install Hall current sensor H1 and Hall current sensor H2; Step 2, setting the sampling time of the Hall current sensor H1 and the Hall current sensor H2; Step 3, setting the minimum sampling time of the Hall current sensor H1 and the Hall current sensor H2; Step 4: According to the current value i obtained by sampling of the Hall current sensor H1 and the Hall current sensor H2 s1 、i s2 , i0 to reconstruct the current and obtain the current values ​​of each phase of A, B, and C.

2. The current reconstruction method of a permanent magnet synchronous motor dual Hall current sensor sampling according to claim 1 is characterized in that: The installation method of the Hall current sensor in step 1 is as follows: the common DC bus open-winding permanent magnet synchronous motor is a dual inverter structure, and the left and right inverters are inverter 1 and inverter 2 respectively; the Hall current sensor H1 samples the upper bridge arm S of inverter 1 11 and S 13 The positive bus current and the lower bridge arm S of inverter 1 14 and S 16 The negative bus current, the Hall current sensor H2 is set at the sampling point of the three-phase winding of the motor, and samples the sum of the three-phase currents, that is, directly obtains three times the zero-sequence current in the zero-sequence current.

3. The current reconstruction method of a permanent magnet synchronous motor dual Hall current sensor sampling according to claim 2 is characterized in that: The expression of zero sequence current is: In formula (1), i0 represents the zero-sequence current value in the zero-sequence circuit, i a 、i b 、i c They respectively represent the phase current values ​​of the three phases A, B, and C in the motor winding.

4. The current reconstruction method of a permanent magnet synchronous motor dual Hall current sensor sampling according to claim 1 is characterized in that: The relationship between the sampling time and PWM in step 2 is: set the sampling time of the Hall current sensor H1 and the Hall current sensor H2 at the peak and trough of the PWM carrier respectively; define t s1 and t s2 is the sampling time of the Hall current sensor H1, and t0 is the sampling time of the Hall current sensor H2; where t s1 ,t s2 are the moments of PWM carrier wave peak and carrier wave valley respectively, t0 is the moment of PWM carrier wave peak, and the carrier wave peak and carrier wave valley are respectively located at the space voltage vector V generated by the two inverters 1 and 2. 77 、V 00 Combined action time.

5. The current reconstruction method of a permanent magnet synchronous motor dual Hall current sensor sampling according to claim 1 is characterized in that: In step 3, the minimum sampling time is greater than the sum of the current ringing time, the A / D digital-to-analog conversion time, the dead time, and the delay time. The expression of the minimum sampling time is: t min >t dead +t delay +t set +t adc (2), In formula (2), t min Indicates the minimum sampling time, t dead Denotes the dead time, t delay Indicates the delay time, t set Represents the current ringing time, t adc Indicates the A / D digital-to-analog conversion time; The minimum action time of the voltage vector combination in the setting space is greater than or equal to the minimum sampling time, that is: my(Tv ij )≥t min (3), In formula (3), Tv ij is the minimum action time of the space voltage vector combination. ij A space voltage vector combination (i, j=1, 2...8) is generated for inverter 1 and inverter 2 respectively.

6. The current reconstruction method of a permanent magnet synchronous motor dual Hall current sensor sampling according to claim 1 is characterized in that: In step 4, at the carrier wave peak moment in a single PWM, the two Hall current sensors H1 and H2 are sampled simultaneously, and the carrier wave peak moment corresponds to the zero space voltage vector combination V 77 The positive bus current flows through the upper bridge arm S of inverter 1. 11 , S 13 , S 15 Flows into the three-phase winding of the motor and passes through the upper bridge arm S of inverter 2 21 , S 23 , S 25 Flow out of the three-phase winding of the motor and return to the DC bus terminal; the Hall current sensor H1 samples the switch device S 11 , S 13 According to Kirchhoff’s current law, S 11 , S 13 The positive bus current is switched by the switching device S 13 , S 15 After the current is split, it is injected into the two-phase windings B and C of the motor, then S 11 , S 13 The current value is the sum of the currents of phases B and C, and the sampling current value is i s1 ; then: i s1 =i b +i c i b and i c They are the phase current values ​​of phase B and phase C in the three-phase winding of the motor respectively; Zero space voltage vector combination V 77 When the inverter 1 and the inverter 2 are in operation, the upper arm switch devices S 11 , S 13 , S 15 , S 21 , S 23 , S 25 All are turned on, and the positive bus current is shunted through the three upper bridge arms of inverter 1 and input into the three phases of motor winding A, B, and C; the Hall current sensor H2 samples the current between the six potentials a1, a2, b1, b2, c1, and c2 between the two inverters 1 and 2, that is, samples the three-phase winding current of the open-winding permanent magnet synchronous motor, and the sampled current value is the sum of the three-phase currents; there is a zero-sequence circuit in the common DC bus open-winding permanent magnet synchronous motor, and the zero-sequence current is sampled by the Hall current sensor H2 through the three-phase winding; the zero-sequence current value is one-third of the sum of the three-phase currents; the current value sampled by the Hall current sensor H2 is i0; then: i o =(i a +i b +i c ) i0 is the zero-sequence current value, i a 、i b 、i c They are the current values ​​of the three phases A, B and C respectively; According to the modulation relationship between the carrier and the PWM wave, at the carrier valley moment, the zero space voltage vector combination V 00 The bus current passes through the lower bridge arm S of inverter 1. 12 , S 14 , S 16 Flows into the three-phase winding of the motor and passes through the lower bridge arm S of inverter 2 22 , S 24 , S 26 Flow out of the three-phase winding of the motor and return to the DC bus terminal; the Hall current sensor H1 samples the switch device S 14 , S 16 According to Kirchhoff's current law, the bus current is divided and flows through S 16 Input motor C phase winding, then S 14 , S 16 The current value between is the C phase current value, and the sampling current value is i s2 ; then: i s2 =i c i c is the phase current value of phase C; The three-phase current information of the motor winding is obtained by reconstructing the sampled current values ​​of the Hall current sensors H1 and H2 at different times; the reconstruction expression is: i s1 is the sum of the currents of phases B and C, i s2 The current value obtained by sampling is the C phase current, i s1 Subtract i s2 is the current value of phase B; i0 is the sum of the three-phase current values ​​obtained by sampling, i0 minus i s1 is the A phase current value.

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