Boost PFC control method based on power closed-loop bus voltage adaptive regulation

Abstract

A BoostPFC control method based on adaptive adjustment of the power closed-loop bus voltage is disclosed, belonging to the field of motor control technology. This invention addresses the problem of low overall efficiency of the motor in the low-speed range of existing air conditioning permanent magnet compressor systems that use constant bus voltage control. The method includes calculating the input power reference value based on the actual dq-axis current and dq-axis setpoint voltage output from the inverter of the compressor drive system; and then, based on the actual bus voltage value, the maximum q-axis current, and the electrical angular velocity ω... e The process involves calculating the input power feedback value, obtaining the bus voltage setpoint, performing voltage PI control based on the bus voltage setpoint and the actual bus voltage, multiplying this by the phase of the grid-side voltage to obtain the PFC current setpoint, performing current PI control with the actual PFC inductor current, and combining this with the feedforward output duty cycle to obtain the PFC switching transistor drive signal. This invention is used for adaptive bus voltage regulation.

Description

Technical Field

[0001] This invention relates to a BoostPFC control method based on adaptive regulation of power closed-loop bus voltage, belonging to the field of motor control technology. Background Technology

[0002] Boost power factor correction (PFC) converters have advantages such as continuous input current, low EMI, and simple switching device driving, and are widely used in air conditioning permanent magnet compressor drive systems.

[0003] The permanent magnet compressor of the air conditioner has a wide speed range. The existing method uses constant bus voltage control, which results in low overall efficiency of the motor in the low speed range, thus limiting the further improvement of system efficiency. Summary of the Invention

[0004] To address the problem that existing air conditioning permanent magnet compressor systems use constant bus voltage control, resulting in low overall efficiency of the motor in the low-speed range, this invention provides a BoostPFC control method based on adaptive adjustment of the power closed-loop bus voltage.

[0005] The present invention provides a BoostPFC control method based on adaptive regulation of power closed-loop bus voltage, comprising:

[0006] The input power reference value of the compressor drive system power loop is calculated based on the actual dq-axis current and dq-axis given voltage output by the inverter after the compressor drive system.

[0007] Then, based on the actual bus voltage, the maximum q-axis current obtained by the compressor drive system operating under boundary conditions close to the maximum undistorted circular rotating vector, and the electric angular velocity ω obtained by sliding mode control, e Calculate the input power feedback value of the power loop of the compressor drive system;

[0008] Power PI control is performed based on the input power reference value and the input power feedback value to obtain the bus voltage setpoint. Limiting control is then performed on the bus voltage setpoint to obtain the range of the bus voltage setpoint.

[0009] Voltage PI control is performed based on the limited bus voltage setpoint and the actual bus voltage to obtain the regulated voltage. The phase of the regulated voltage is multiplied by the phase of the grid-side voltage to obtain the PFC current setpoint. Then, current PI control is performed based on the PFC current setpoint and the actual PFC inductor current to obtain the current loop output duty cycle. The PFC switching transistor drive signal is obtained by summing the current loop output duty cycle and the feedforward output duty cycle.

[0010] According to the BoostPFC control method based on adaptive regulation of power closed-loop bus voltage of the present invention, the input power reference value is expressed as P. ref The acquisition process is as follows:

[0011] The inverter of the compressor drive system adopts SVPWM modulation and uses a sensorless vector control with the speed loop as the outer loop and the current loop as the inner loop.

[0012] Calculate the actual input power P of the compressor drive system power loop. o :

[0013] P o =1.5(u dref i d +u qref i q ),

[0014] In the formula u dref Given a voltage along the d-axis, i d For the actual d-axis current, u qref Given a voltage along the q-axis, i q This is the actual q-axis current;

[0015] For the actual input power P o Peak sampling is performed to obtain the peak input power. After adding a DC bias ΔP to the peak input power, the reference input power value P is obtained. ref .

[0016] According to the BoostPFC control method based on adaptive regulation of power closed-loop bus voltage of the present invention, the maximum q-axis current i qm The method to obtain it is as follows:

[0017] The dq-axis stator voltage equation is:

[0018] u d =-ω e L q i q ,

[0019]

[0020] In the formula u d L represents the actual d-axis voltage output by the subsequent inverter. q U is the q-axis inductance of the motor. q The actual q-axis voltage output by the subsequent inverter, where t is time, and R... s ψ is the stator resistance of the motor. f For motor magnetic flux;

[0021] The boundary conditions under which the compressor drive system operates close to the maximum undistorted circular rotation vector are:

[0022]

[0023] In the formula u dc This is the actual value of the bus voltage;

[0024] The maximum q-axis current i was calculated. qm The expression:

[0025]

[0026] According to the BoostPFC control method based on adaptive regulation of power closed-loop bus voltage of the present invention, the electric angular velocity ω e The method to obtain it is as follows:

[0027] Sample bus voltage actual value u dc Sliding mode control was then performed to obtain the electric angular velocity ω. e .

[0028] According to the BoostPFC control method based on adaptive regulation of power closed-loop bus voltage of the present invention, the input power feedback value of the compressor drive system power loop is expressed as P. m Input power feedback value P m The maximum current i passing through the q-axis qm The calculated limit input power of the compressor drive system under distortion-free conditions:

[0029]

[0030] According to the BoostPFC control method based on adaptive regulation of power closed-loop bus voltage of the present invention, the method for determining the range of the bus voltage setpoint is as follows:

[0031] Input power reference value P ref With input power feedback value P m After subtraction, power PI control is performed to obtain the bus voltage setpoint u. ref To ensure the output waveform of the front-stage Boost circuit of the compressor drive system is not distorted, and the bus voltage setpoint u... ref The bus voltage setpoint u is controlled to not exceed the bus capacitor withstand voltage. ref The range is between 311V and 450V.

[0032] According to the BoostPFC control method based on adaptive regulation of power closed-loop bus voltage of the present invention, the method for obtaining the PFC switching transistor drive signal is as follows:

[0033] The bus voltage setpoint u after limiting ref Compared with the actual value of bus voltage u dcAfter taking the difference, voltage PI control is applied to obtain the regulated voltage;

[0034] By measuring the output voltage u of the front-stage rectifier bridge of the compressor drive system in Phase-locked loop (PLL) control is used to obtain the phase of the grid-side voltage, and the output voltage u is obtained. in 100Hz fundamental phase and grid-side voltage u g fundamental phase The relationship is:

[0035] The current setpoint i of the PFC is obtained by multiplying the phase of the regulated voltage by the phase of the grid-side voltage. ref Set the PFC current setpoint i ref The actual value of the inductor current i of PFC L After differential calculation, current PI control is performed to obtain the current loop output duty cycle;

[0036] The duty cycle of the current loop output is compared with the duty cycle of the feedforward circuit output. ff The sum of the two signals, compared with the carrier wave, generates a PWM wave which serves as the switching drive signal for the PFC transistor. ff =1-u in / u ref .

[0037] The beneficial effects of the present invention are as follows: The method of the present invention is based on motor boundary voltage monitoring, which realizes automatic matching between bus voltage and compressor load and speed, and can improve the efficiency of compressor drive system in low-speed operating range.

[0038] This invention provides an adaptive control method for the bus voltage of a BoostPFC converter. Building upon the traditional dual-loop voltage and current control, it proposes an adaptive bus voltage adjustment strategy. By introducing a power control loop as the outer loop of the converter control system, and based on the limit power obtained from the bus voltage and motor voltage constraints, the method follows the actual power changes of the motor, achieving automatic matching between the bus voltage and the compressor load and speed, effectively improving the system's operating efficiency. Attached Figure Description

[0039] Figure 1 This is a control block diagram of a BoostPFC control method based on adaptive power closed-loop bus voltage regulation for a compressor drive system; u in the diagram g i is the grid-side input voltage. g The grid-side input current is represented by D1 to D4, which are the four diodes in the rectifier circuit. L is the inductor, and u is the voltage. in U is the output voltage of the front-end rectifier bridge, S is the PFC switch, D is the freewheeling diode, C is the bus capacitor, and S1 to S6 are the six switches in the subsequent inverter; gU represents the grid-side voltage amplitude. ref The amplitude of the bus voltage setpoint;

[0040] Figure 2 This is the control block diagram of the downstream inverter; ω in the diagram * For the speed ring setpoint, i qref Given the q-axis current, i dref U is the given value for the d-axis current. dc This is the actual value of the DC bus voltage; i abc For the inverter to output three-phase current, i α Let i be the α-axis current. β Let θ be the β-axis current and θ be the angular velocity of the voltage rotation vector.

[0041] Figure 3 This is a block diagram of the power control loop in the method of the present invention;

[0042] Figures 4 to 9 To achieve different motor operating frequencies f m Below is a graph showing the motor operating efficiency results using the control method of this invention;

[0043] in Figure 4 For U dc =320V, f m The graph shows the motor's operating efficiency at 20Hz.

[0044] Figure 5 For U dc =320V, f m The graph shows the motor's operating efficiency at 60Hz.

[0045] Figure 6 For U dc =350V, f m The graph shows the motor's operating efficiency at 20Hz.

[0046] Figure 7 For U dc =350V, f m The graph shows the motor's operating efficiency at 60Hz.

[0047] Figure 8 For U dc =380V, f m The graph shows the motor's operating efficiency at 20Hz.

[0048] Figure 9 For U dc =380V, f m The graph shows the motor's operating efficiency at 60Hz.

[0049] Figure 10The waveform diagram shows the adaptive adjustment of voltage and current at an operating frequency of 20Hz.

[0050] Figure 11 The waveform diagram shows the adaptive adjustment of voltage and current at an operating frequency of 40Hz.

[0051] Figure 12 The waveform diagram shows the adaptive adjustment of voltage and current at an operating frequency of 60Hz.

[0052] Figure 13 The figure shows the experimental statistical results of the system operating efficiency of the method of the present invention at different operating frequencies. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0055] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0056] Specific Implementation Method 1: Combination Figure 1 As shown, this invention provides a BoostPFC control method based on adaptive regulation of power closed-loop bus voltage, including:

[0057] The input power reference value of the compressor drive system power loop is calculated based on the actual dq-axis current and dq-axis given voltage output by the inverter after the compressor drive system.

[0058] Then, based on the actual bus voltage, the maximum q-axis current obtained by the compressor drive system operating under boundary conditions close to the maximum undistorted circular rotating vector, and the electric angular velocity ω obtained by sliding mode control, e Calculate the input power feedback value of the power loop of the compressor drive system;

[0059] Power PI control is performed based on the input power reference value and the input power feedback value to obtain the bus voltage setpoint. Limiting control is then performed on the bus voltage setpoint to obtain the range of the bus voltage setpoint.

[0060] Voltage PI control is performed based on the limited bus voltage setpoint and the actual bus voltage to obtain the regulated voltage. The phase of the regulated voltage is multiplied by the phase of the grid-side voltage to obtain the PFC current setpoint. Then, current PI control is performed based on the PFC current setpoint and the actual PFC inductor current to obtain the current loop output duty cycle. The PFC switching transistor drive signal is obtained by summing the current loop output duty cycle and the feedforward output duty cycle.

[0061] This implementation analyzes the Space Vector Pulse Width Modulation (SVPWM) control scheme used on the motor side, clarifying the intrinsic relationship between the bus voltage and the motor voltage vector under the voltage boundary conditions (approaching the maximum undistorted circular rotating vector boundary conditions) before the motor enters the field weakening region. It also analyzes driver losses, establishes the relationship between system efficiency and bus voltage, and proposes an adaptive bus voltage adjustment strategy based on the traditional dual-loop voltage and current control. By introducing a power control loop as the outer loop of the converter control system, the limit power obtained from the bus voltage and motor voltage constraints follows the actual power change information of the motor, achieving automatic matching of bus voltage with compressor load and speed, effectively improving system operating efficiency.

[0062] Furthermore, combined with Figure 2 and Figure 3 As shown, the input power reference value is represented as P. ref The acquisition process is as follows:

[0063] The inverter of the compressor drive system adopts SVPWM modulation and uses a sensorless vector control with the speed loop as the outer loop and the current loop as the inner loop.

[0064] Calculate the actual input power P of the compressor drive system power loop. o :

[0065] P o =1.5(u dref i d +u qref i q (1)

[0066] In the formula u dref Given a voltage along the d-axis, i d For the actual d-axis current, u qref Given a voltage along the q-axis, i q This is the actual q-axis current;

[0067] To ensure the drive system does not overmodulate and to compensate for inverter losses, the actual input power P... oPeak sampling is performed to obtain the peak input power. After adding a DC bias ΔP to the peak input power, the reference input power value P is obtained. ref .

[0068] In this embodiment, combined with Figure 3 As shown, the maximum q-axis current i qm The method to obtain it is as follows:

[0069] The dq-axis stator voltage equation is:

[0070] u d =-ω e L q i q (2)

[0071]

[0072] In the formula u d L represents the actual d-axis voltage output by the subsequent inverter. q U is the q-axis inductance of the motor. q The actual q-axis voltage output by the subsequent inverter, where t is time, and R... s ψ is the stator resistance of the motor. f For motor magnetic flux;

[0073] The boundary conditions under which the compressor drive system operates close to the maximum undistorted circular rotation vector are:

[0074]

[0075] In the formula u dc This is the actual value of the bus voltage;

[0076] The maximum q-axis current i was calculated. qm The expression:

[0077]

[0078] Electric angular velocity ω e The method to obtain it is as follows:

[0079] Sample bus voltage actual value u dc Sliding mode control was then performed to obtain the electric angular velocity ω. e .

[0080] Furthermore, the input power feedback value of the compressor drive system power loop is expressed as P. m Input power feedback value P m The maximum current i passing through the q-axis qm The calculated limit input power of the compressor drive system under distortion-free conditions:

[0081]

[0082] In this embodiment, the method for determining the range of the bus voltage setpoint is as follows:

[0083] Input power reference value P ref With input power feedback value P m After subtraction, power PI control is performed to obtain the bus voltage setpoint u. ref To ensure the output waveform of the front-stage Boost circuit of the compressor drive system is not distorted, and the bus voltage setpoint u... ref The bus voltage setpoint u is controlled to not exceed the bus capacitor withstand voltage. ref The range is between 311V and 450V.

[0084] Finally, the method for obtaining the switching transistor drive signal of PFC is as follows:

[0085] The bus voltage setpoint u after limiting ref Compared with the actual value of bus voltage u dc After taking the difference, voltage PI control is applied to obtain the regulated voltage;

[0086] By measuring the output voltage u of the front-stage rectifier bridge of the compressor drive system in Phase-locked loop (PLL) control is used to obtain the phase of the grid-side voltage. Fourier analysis reveals that the output voltage u... in 100Hz fundamental phase and grid-side voltage u g fundamental phase The relationship is: For the rectifier bridge output voltage u in After filtering and phase-locking, the grid-side voltage u can be obtained through phase transformation. g fundamental phase The current setpoint i of the PFC is obtained by multiplying the phase of the regulated voltage by the phase of the grid-side voltage. ref Set the PFC current setpoint i ref The actual value of the inductor current i of PFC L After differential calculation, current PI control is performed to obtain the current loop output duty cycle;

[0087] The duty cycle of the current loop output is compared with the duty cycle of the feedforward circuit output. ff The sum of the two signals, compared with the carrier wave, generates a PWM wave which serves as the switching drive signal for the PFC transistor. ff =1-u in / u ref .

[0088] Combination Figure 2As shown, the motor of this invention employs dual closed-loop vector control, with an inner loop being a current loop and an outer loop being a speed loop. The difference between the reference value and the feedback value of the rotational speed is adjusted by a PI controller, as is the difference between the reference value and the feedback value of the dq-axis current. The three-phase stator current of the motor is obtained as the dq-axis current in a two-phase rotating coordinate system through Clark and Park coordinate transformation. Specific implementation examples:

[0090] The effectiveness of the proposed control method was verified on a permanent magnet synchronous compressor driver platform based on a Boost PFC converter. The experimental platform parameters were set as follows: mains voltage 220V, mains frequency 50Hz, boost inductor 260μH, and bus capacitance 940μF. All control algorithms were implemented in the Renesas RX24T, with the update frequency of switching and voltage / current sampling values ​​set to 40kHz.

[0091] Combination Figures 4 to 9 At different motor operating frequencies f m Next, take U respectively dc =320V, 350V, 380V; it can be seen that when the motor operating frequency f m At 20Hz and 60Hz respectively, the motor efficiency decreased as the bus voltage increased, verifying the correctness of the method of the present invention.

[0092] Figures 10 to 12 The figures show the experimental results of the bus voltage adaptive strategy, corresponding to the voltage and current experimental waveforms at different motor operating frequencies. As can be seen from the figures, after applying the bus voltage adaptive strategy, the bus voltage and the motor speed are adaptively matched. As the motor speed increases, the bus voltage also gradually increases accordingly. During the bus voltage matching process, the system operates stably without significant vibration, verifying the feasibility of the method of this invention.

[0093] Figure 13 The figure shows the changes in system operating efficiency at different operating frequencies after applying the adaptive bus voltage strategy of the present invention. As can be seen from the figure, the system has not yet reached its maximum efficiency within the test range of motor operating frequency. Therefore, the overall operating efficiency increases with the increase of motor operating frequency within the test range. After using the method of the present invention for control, the overall operating efficiency of the system in the low speed range is significantly improved compared with the traditional constant bus voltage, with an improvement of up to 1.5%, which verifies the effectiveness of the method of the present invention.

[0094] In summary, this invention demonstrates that the method can improve the efficiency of the compressor drive system in the low-speed operating range.

[0095] The BoostPFC control method based on adaptive regulation of power closed-loop bus voltage proposed in this invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A BoostPFC control method based on adaptive regulation of power closed-loop bus voltage, characterized in that... include, The input power reference value of the compressor drive system power loop is calculated based on the actual dq-axis current and dq-axis given voltage output by the inverter after the compressor drive system. According to the bus voltage actual value, the q-axis maximum current obtained by the compressor driving system working in the boundary condition close to the maximum distortionless circular rotating vector, and the electric angular velocity ω obtained by the sliding mode control, the input power feedback value of the compressor driving system power loop is calculated e . Power PI control is performed based on the input power reference value and the input power feedback value to obtain the bus voltage setpoint. Limiting control is then performed on the bus voltage setpoint to obtain the range of the bus voltage setpoint. Voltage PI control is performed based on the limited bus voltage setpoint and the actual bus voltage to obtain the regulated voltage. The regulated voltage is then multiplied by the phase of the grid-side voltage to obtain the PFC current setpoint. Then, based on the current setpoint of PFC and the actual value of PFC inductor current, current PI control is performed to obtain the current loop output duty cycle. The switching drive signal of PFC is obtained by summing the duty cycle of the current loop output and the duty cycle of the feedforward circuit output.

2. The BoostPFC control method based on adaptive regulation of power closed-loop bus voltage according to claim 1, characterized in that, The input power reference value is denoted P ref The obtaining procedure is: The inverter of the compressor drive system adopts SVPWM modulation and uses a sensorless vector control with the speed loop as the outer loop and the current loop as the inner loop. Calculate the actual input power P of the compressor drive system power loop. o : P o =1.5(in dref and d +in qref and q ), In the formula u dref Given a voltage along the d-axis, i d For the actual d-axis current, u qref Given a voltage along the q-axis, i q This is the actual q-axis current; For the actual input power P o Peak sampling is performed to obtain the peak input power. After adding a DC bias ΔP to the peak input power, the reference input power value P is obtained. ref .

3. The BoostPFC control method based on adaptive regulation of power closed-loop bus voltage according to claim 2, characterized in that, q-axis maximum current i qm The method to obtain it is as follows: The dq-axis stator voltage equation is: u d =-ω e L q i q , In the formula u d L represents the actual d-axis voltage output by the subsequent inverter. q U is the q-axis inductance of the motor. q The actual q-axis voltage output by the subsequent inverter, where t is time, and R... s ψ is the stator resistance of the motor. f For motor magnetic flux; The boundary conditions under which the compressor drive system operates close to the maximum undistorted circular rotation vector are: In the formula u dc This is the actual value of the bus voltage; The maximum q-axis current i was calculated. qm The expression:

4. The BoostPFC control method based on adaptive regulation of power closed-loop bus voltage according to claim 3, characterized in that, Electric angular velocity ω e The method to obtain it is as follows: Sample bus voltage actual value u dc Sliding mode control was then performed to obtain the electric angular velocity ω. e .

5. The BoostPFC control method based on adaptive regulation of power closed-loop bus voltage according to claim 4, characterized in that, The input power feedback value of the compressor drive system power loop is represented by P. m Input power feedback value P m The maximum current i through the q-axis qm The calculated limit input power of the compressor drive system under distortion-free conditions:

6. The BoostPFC control method based on adaptive regulation of power closed-loop bus voltage according to claim 5, characterized in that, The method for determining the range of the bus voltage setpoint is as follows: Input power reference value P ref With input power feedback value P m After subtraction, power PI control is performed to obtain the bus voltage setpoint u. ref To ensure the output waveform of the front-stage Boost circuit of the compressor drive system is not distorted, and the bus voltage setpoint u... ref The bus voltage setpoint u is controlled to not exceed the bus capacitor withstand voltage. ref The range is between 311V and 450V.

7. The BoostPFC control method based on adaptive regulation of power closed-loop bus voltage according to claim 6, characterized in that, The method for obtaining the switching transistor drive signal in PFC is as follows: The bus voltage setpoint u after limiting ref Actual value of bus voltage u dc After taking the difference, voltage PI control is applied to obtain the regulated voltage; By measuring the output voltage u of the front-stage rectifier bridge of the compressor drive system in Phase-locked loop (PLL) control is used to obtain the phase of the grid-side voltage, and the output voltage u is obtained. in 100Hz fundamental phase and grid-side voltage u g fundamental phase The relationship is: The current setpoint i of the PFC is obtained by multiplying the phase of the regulated voltage by the phase of the grid-side voltage. ref Set the PFC current setpoint i ref The actual value of the inductor current i of PFC L After differential calculation, current PI control is performed to obtain the current loop output duty cycle; The duty cycle of the current loop output is compared with the duty cycle of the feedforward circuit output. ff The sum of the two signals, compared with the carrier wave, generates a PWM wave which serves as the switching drive signal for the PFC transistor. ff =1-u in / u ref .

Images