A control method and device for a vehicle-mounted refrigerator compressor

Abstract

The application discloses a kind of vehicle refrigerator compressor control method, belong to vehicle refrigeration equipment control technical field.The method uses cascade control structure to control BOOST circuit.The method includes: obtaining compressor speed, counter electromotive force peak value, vehicle input voltage, bus voltage, inductance current, cross axis current and stator resistance in each control cycle;Calculate target bus voltage value;Calculate target duty cycle;The target bus voltage value is carried out slope limiting processing;Calculate inductance current reference value;Calculate duty cycle correction amount;According to target duty cycle and duty cycle correction amount, obtain final duty cycle instruction, and output to BOOST circuit power switch tube.This application makes bus voltage change in real time with compressor speed, solves the problem that fixed modulation margin leads to low speed loss and high speed dynamic response difference.

Description

Technical Field

[0001] This application relates to the field of vehicle-mounted refrigeration equipment control technology, specifically to a vehicle-mounted refrigerator compressor control method and device. Background Technology

[0002] In existing vehicle refrigerator compressor control schemes, the bus voltage and compressor speed are disconnected. In the direct-drive scheme, the bus voltage is the fluctuating vehicle battery voltage (10V~32V), which does not change with the target compressor speed. In the fixed-boost scheme, the bus voltage is boosted to a certain constant value (e.g., 36V / 48V) and then remains unchanged. In the lookup table method or open-loop PWM voltage regulation scheme, the voltage is output according to a preset table and cannot be adjusted according to real-time operating conditions. The common essence of these three schemes is that the bus voltage is determined by the power supply or a preset value, rather than by the actual operating state of the compressor. There is no real-time, adaptive coupling relationship between the bus voltage and the compressor speed.

[0003] The above-mentioned scheme causes the bus voltage to deviate from the actual needs of the compressor under different speeds and load conditions: at low speeds, the bus voltage is too high, increasing inverter switching losses and reducing efficiency under light loads; at high speeds, the bus voltage is insufficient, preventing the compressor from reaching the target speed and limiting cooling capacity; when the load suddenly increases, the compressor will require more power instantaneously, and if the BOOST circuit cannot immediately provide this energy, the bus voltage will drop due to "supply falling short of demand." The existing pure feedback dual-loop control structure's adjustment path is "load change → bus voltage change → voltage outer loop → current inner loop → duty cycle correction." This scheme has a long signal path and a delayed response, resulting in a severe drop in bus voltage, ultimately causing compressor speed fluctuations. The inability to dynamically match voltage and speed leads to a decrease in overall unit energy efficiency. Summary of the Invention

[0004] To overcome the above-mentioned technical defects, this application provides a vehicle refrigerator compressor control method and device. By acquiring the real-time operating parameters of the compressor in each control cycle, the target bus voltage value is calculated using the dynamic modulation margin method, the target duty cycle is calculated by combining the synchronous rectification efficiency correction method, and the bus voltage is adaptively matched with the compressor speed in real time through feedforward and feedback dual closed-loop control, thereby improving the overall energy efficiency.

[0005] To solve the above problems, this application is implemented according to the following technical solution:

[0006] This application provides a control method for a vehicle-mounted refrigerator compressor. The method is used for a vehicle-mounted refrigerator compressor, which is powered by a BOOST circuit. The method includes:

[0007] During each control cycle, the compressor speed, back EMF peak value, on-board input voltage, bus voltage, inductor current, quadrature shaft current, and stator resistance are acquired.

[0008] The target bus voltage value is calculated using a dynamic modulation margin method based on the compressor speed, back EMF peak value, quadrature shaft current, and stator resistance. The dynamic modulation margin method is a control strategy that introduces a voltage margin that changes in real time with the compressor speed when calculating the target bus voltage value.

[0009] Based on the target bus voltage, on-board input voltage, quadrature axis current and compressor speed, the target duty cycle is calculated using the synchronous rectification efficiency correction method.

[0010] The target bus voltage value is subjected to slope limiting processing to obtain a slope-limited bus voltage setpoint.

[0011] Based on the given value of the bus voltage after the slope limitation, the bus voltage, the inductor current and the target duty cycle, the final duty cycle command is obtained through the feedforward method.

[0012] The final duty cycle command is output to the power switch of the BOOST circuit to control the BOOST circuit to boost the vehicle input voltage to the target bus voltage value.

[0013] This application also provides a vehicle-mounted refrigerator compressor control device, including:

[0014] BOOST circuit, including power switching transistors;

[0015] Voltage sampling circuit, used to collect bus voltage and vehicle input voltage;

[0016] Current sampling circuit, used to collect inductor current;

[0017] Back EMF observer is used to estimate compressor speed and peak back EMF in real time;

[0018] A processor is used to execute the aforementioned vehicle-mounted refrigerator compressor control method.

[0019] Compared with the prior art, the beneficial effects of this application are:

[0020] This application acquires real-time operating parameters of the compressor in each control cycle and employs a dynamic modulation margin method to make the target bus voltage change in real time with the speed—automatically reducing the margin at low speeds to reduce switching losses and automatically increasing the margin at high speeds to meet dynamic response requirements, thus solving the problem of mismatch between fixed modulation margin and speed. It also employs a synchronous rectification efficiency correction method to match the duty cycle calculation with the actual efficiency of the BOOST circuit, solving the problem of output voltage deviation from the target value caused by fixed efficiency assumptions. Furthermore, it uses a dual closed-loop control of feedforward and feedback, directly introducing compressor power changes into the inner current loop, so that the bus voltage is compensated before deviation occurs when the load changes abruptly, solving the problem of lag in the response of a pure feedback structure. In addition, combining the above beneficial effects, this application enables the bus voltage to adaptively match the compressor speed in real time, improving the overall energy efficiency. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings, wherein:

[0023] Figure 1 This is a flowchart illustrating the steps of a vehicle-mounted refrigerator compressor control method provided in this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. It should be understood that the step numbers used herein are only for convenience of description and are not intended to limit the order of execution of the steps.

[0025] In this application, _f represents the filtered value; square brackets [k] represent the value of the kth control cycle, and [k-1] represent the value of the (k-1)th control cycle (i.e., the previous cycle); Ts represents the duration of the control cycle; in the field of motor control, filtering the sampled signal is common and necessary. The filtering process is a well-known technique in the art and is not innovative. It is not a necessary technical feature of this application and therefore will not be described in detail here.

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. In an exemplary embodiment, such as Figure 1 As shown, this application provides a control method for a vehicle-mounted refrigerator compressor. The method is used for a vehicle-mounted refrigerator compressor powered by a BOOST circuit. The BOOST circuit is controlled by a cascade control structure. The cascade control structure includes a voltage outer loop and a current inner loop. The output terminal of the voltage outer loop is connected to the input terminal of the current inner loop. The method includes steps 101 to 106, specifically:

[0027] Step 101: In each control cycle, acquire the compressor speed, back EMF peak value, on-board input voltage, bus voltage, inductor current, quadrature shaft current, and stator resistance.

[0028] Preferably, the control chip acquires the compressor's current rotor speed ω and the corresponding back EMF peak value E_bemf in real time using the FOC algorithm or a sensorless observer. The on-board input voltage and bus voltage are acquired through a resistor divider sampling circuit, converted into digital quantities by the control chip's ADC module, and then used in calculations. The inductor current is detected by a sampling resistor connected in series in the BOOST circuit. The quadrature-axis current Iq is calculated in real time by the control chip using the FOC algorithm to perform Clark and Park transformations on the acquired three-phase currents. The stator resistance Rs is an inherent parameter of the motor and is acquired offline before motor startup.

[0029] Step 102: Calculate the target bus voltage value using the dynamic modulation margin method based on the compressor speed, back EMF peak value, quadrature shaft current, and stator resistance; the dynamic modulation margin method is a control strategy that introduces a voltage margin that changes in real time with the compressor speed when calculating the target bus voltage value.

[0030] Specifically, based on the motor parameter model, the target bus voltage value at the current speed is calculated using the following formula:

[0031] Vbus∗=k1⋅Ebemf+k2⋅Iq⋅Rs+Vmargin(ω);

[0032] in,

[0033] k1 is the back electromotive force utilization factor (typical value 1.10~1.25).

[0034] k2⋅Iq⋅Rs is the current loop voltage drop compensation term;

[0035] V_margin(ω) is the dynamic modulation margin that varies with the compressor speed. It should be noted that V_margin(ω) is not a fixed value, which is the key difference between this application and existing fixed margin schemes. Vmargin(ω) is a continuous domain expression, indicating that "the margin is a function of the speed." However, in a digital control system, all operations are discrete—a calculation is performed once per control cycle, requiring a clear distinction between the "value of the current cycle" and the "value of the previous cycle." Therefore, it needs to be written in a discrete form such as Vmargin[k] and ω_f[k].

[0036] Furthermore, the target bus voltage value is obtained by adding the back electromotive force utilization term, the current loop voltage drop compensation term, and the dynamic modulation margin; the dynamic modulation margin is a nonlinear function dynamically adjusted according to the compressor speed, speed change rate, quadrature shaft current, and on-board input voltage in the current control cycle of the compressor; the speed change rate is the difference between the compressor speed in the current control cycle and the compressor speed in the previous control cycle divided by the control cycle duration.

[0037] Preferably, the dynamic modulation margin is written as a recursive expression, specifically in the form of:

[0038] Vmargin[k]=β·Vmargin[k-1]+(1-β)·Fm(ω_f[k], Δω[k], Iq_f[k], Vin[k]);

[0039] in,

[0040] Δω[k]=(ω_f[k]-ω_f[k-1]) / Ts;

[0041] Fm can be defined as:

[0042]

[0043] in,

[0044] V0 is the basic modulation margin;

[0045] a1·|ω_f[k]| indicates that the higher the rotational speed, the larger the modulation margin, which is used to compensate for the incremental demand on bus voltage at high rotational speeds;

[0046] a2·|Δω[k]| indicates that the more violent the acceleration or deceleration, the larger the temporary margin, which is used to compensate for voltage fluctuations during dynamic processes;

[0047] a3·|Iq_f[k]| indicates that the larger the load, the larger the voltage drop compensation margin, which is used to compensate for the stator resistance voltage drop under high current.

[0048] a1, a2, and a3 are preset positive numbers;

[0049] G(Vin[k]) is the input voltage correction function. When the on-board input voltage is lower than the nominal voltage, the modulation margin is increased to compensate for the effect of the increased duty cycle of the BOOST circuit under low voltage input.

[0050] β is the margin recursive smoothing coefficient, which can be 0 < β < 1. The closer β is to 1, the smoother the margin change and the slower the response to disturbances. The closer β is to 0, the faster the margin response, but the smoothness decreases.

[0051] Preferably, G(Vin[k]) = max(0, Vin_nom - Vin[k]);

[0052] This indicates that when the on-board input voltage is lower than the nominal voltage, the target margin should be appropriately increased or corrected.

[0053] Vbus_raw[k]=k1·E_f[k]+k2·Iq_f[k]·Rs+Vmargin[k];

[0054] in,

[0055] k1·E_f[k] represents the base voltage requirement corresponding to the back electromotive force;

[0056] k2·Iq_f[k]·Rs is the current loop voltage drop compensation term;

[0057] Vmargin[k] is the dynamic modulation margin.

[0058] Furthermore, the target bus voltage value is constrained by upper and lower limits using the clamp function.

[0059] Specifically, add upper and lower limit constraints:

[0060] Vbus_raw[k]=clamp(k1·E_f[k]+k2·Iq_f[k]·Rs+Vmargin[k],

[0061] Vbus_min,

[0062] Vbus_max );

[0064] in,

[0065] Vbus_min is the minimum allowable bus voltage;

[0066] Vbus_max is the maximum allowable bus voltage;

[0067] k1 is the back electromotive force utilization coefficient, and k2 is the current voltage drop compensation coefficient, both of which are preset constants.

[0068] Step 103: Calculate the target duty cycle using the synchronous rectification efficiency correction method based on the target bus voltage, on-board input voltage, quadrature shaft current, and compressor speed.

[0069] Furthermore, the synchronous rectification efficiency correction method is a control strategy that introduces an efficiency correction factor that dynamically changes with the compressor speed and quadrature shaft current;

[0070] The target duty cycle is calculated from the target bus voltage, the on-board input voltage, and the synchronous rectification efficiency correction factor; the synchronous rectification efficiency correction factor is a function of the compressor speed and the quadrature shaft current.

[0071] Specifically, the synchronous rectification efficiency correction factor can be written as a function related to compressor speed and current:

[0072] ηSR[k]=η0-b1·|Iq_f[k]|-b2·|ω_f[k]|-b3·|Vin_nom-Vin[k]|;

[0073] Preferably, a recursive filtering method is used:

[0074] ηSR[k]=γ·ηSR[k-1]+(1-γ)·Fη(ω_f[k], Iq_f[k], Vin[k]);

[0075] in,

[0076] Fη(ω_f[k], Iq_f[k], Vin[k])=η0-b1·|Iq_f[k]|-b2·|ω_f[k]|-b3·|Vin_nom-Vin[k]|;

[0077] Furthermore, the synchronous rectification efficiency correction factor is constrained by the clamp function.

[0078] Specifically, upper and lower limits are imposed on the synchronous rectification efficiency correction factor:

[0079] ηSR[k]=clamp(ηSR[k], ηmin, ηmax)

[0080] The feedforward duty cycle (target duty cycle) of synchronous rectification BOOST can be written as:

[0081] Dff[k]=1-ηSR[k]·Vin[k] / Vbus_ref[k];

[0082] Limit the target duty cycle:

[0083] Dff[k]=clamp(Dff[k], Dmin, Dmax);

[0084] in,

[0085] Dff[k] is the feedforward duty cycle (target duty cycle) calculated based on the input voltage and the target bus voltage.

[0086] Dmin is the minimum allowable duty cycle;

[0087] Dmax is the maximum allowed duty cycle.

[0088] It should be noted that the duty cycle calculation D=1-Vin·η / Vbus (understandably, this application makes an adaptive transformation to the duty cycle formula) depends on the value of the efficiency η. Conventional schemes assume η to be a fixed value (such as 90% or 95%) when calculating the duty cycle, but the actual efficiency of the BOOST circuit is not constant—when the compressor speed increases, the switching frequency of the power switch increases, the switching loss increases, and the efficiency decreases; when the load current (i.e., the quadrature axis current in this application) increases, the conduction loss (I²R) increases, and the efficiency also decreases accordingly.

[0089] The assumption of a fixed efficiency leads to deviations in duty cycle calculation: at low speed and light load, the actual efficiency is higher than the assumed value, and the duty cycle calculated based on the fixed efficiency causes the output voltage to be higher than the target value, resulting in energy waste; at high speed and heavy load, the actual efficiency is lower than the assumed value, and the duty cycle calculated based on the fixed efficiency causes the output voltage to be lower than the target value, the compressor cannot obtain sufficient power supply voltage, and the output is limited.

[0090] To address the aforementioned issues, this application defines the efficiency correction factor ηSR as a function of compressor speed ω and quadrature-axis current Iq, and updates it in real time using a recursive filtering method. This ensures that the efficiency value used in the duty cycle calculation matches the actual efficiency of the BOOST circuit. Consequently, across the entire speed and load range, the actual output voltage of the BOOST circuit accurately tracks the target voltage, avoiding energy waste caused by excessively high voltage under light loads and insufficient compressor output caused by excessively low voltage under heavy loads. This improves system efficiency and voltage control accuracy across the entire operating range.

[0091] Step 104: Perform slope limiting processing on the target bus voltage value to obtain the slope-limited bus voltage setpoint.

[0092] Further, the bus voltage difference is calculated based on the target bus voltage value and the bus voltage of the previous control cycle;

[0093] When the bus voltage difference is greater than the preset maximum voltage rise step size in a single cycle, the bus voltage setpoint is set to the sum of the bus voltage in the previous control cycle and the rise step size.

[0094] When the bus voltage difference is less than the negative value of the preset maximum voltage drop step size in a single cycle, the bus voltage setpoint is set to the difference between the bus voltage in the previous control cycle and the drop step size.

[0095] When the bus voltage difference is between the negative value of the falling step and the rising step, the bus voltage setpoint is set to the target bus voltage value.

[0096] Step 105: Based on the given value of the bus voltage after slope limitation, the bus voltage, the inductor current and the target duty cycle, obtain the final duty cycle command through the feedforward method.

[0097] Furthermore, based on the deviation between the given bus voltage after slope limitation and the bus voltage, the inductor current reference value is calculated using the feedforward method.

[0098] The duty cycle correction is calculated based on the deviation between the inductor current reference value and the inductor current.

[0099] The final duty cycle command is obtained based on the target duty cycle and the duty cycle correction amount.

[0100] Furthermore, the feedforward method is a control strategy that adjusts the inductor current reference value in advance based on changes in compressor power;

[0101] The bus voltage error is calculated based on the given bus voltage value after the slope limitation and the bus voltage itself.

[0102] Obtain the compressor power feedforward;

[0103] The inductor current reference value is calculated based on the bus voltage error and the compressor power feedforward.

[0104] Specifically, on the outer ring side, the bus voltage error is defined as follows:

[0105] ev[k] = Vbus_ref[k] - Vbus[k];

[0106] The outer loop output is the BOOST inductor current reference value IL_ref[k]:

[0107] IL_ref[k]=IL_ref[k-1]+Kpv·(ev[k]-ev[k-1])+Kiv·Ts·ev[k]+Kfv·ΔPcomp[k];

[0108] in,

[0109] Kpv is the voltage loop proportionality coefficient;

[0110] Kiv is the voltage loop integral coefficient;

[0111] Kfv is the compressor power feedforward coefficient;

[0112] ΔPcomp[k] is the feedforward quantity for compressor load change.

[0113] Furthermore, the current power of the compressor is calculated based on the compressor speed and the quadrature-axis current;

[0114] The difference between the current power of the compressor and the compressor power in the previous control cycle is used as the power feedforward.

[0115] The compressor power feedforward can be estimated from the compressor speed and q-axis current:

[0116] Pcomp[k]=Kt·ω_f[k]·Iq_f[k]+Ploss[k];

[0117] ΔPcomp[k]=Pcomp[k]-Pcomp[k-1];

[0118] in,

[0119] Kt is the torque coefficient, which is determined by the compressor motor parameters;

[0120] Ploss[k] is the estimated value of compressor loss, which can be pre-calibrated based on the compressor motor parameters or obtained by looking up a table.

[0121] Preferably, the output of the outer loop is limited:

[0122] IL_ref[k]=clamp(IL_ref[k], IL_min, IL_max);

[0123] On the inner loop side, calculate the recursive expression for the BOOST inductor current loop.

[0124] Define inductor current error:

[0125] ei[k] = IL_ref[k] - IL[k];

[0126] Current loop output duty cycle correction:

[0127] Dfb[k]=Dfb[k-1]+Kpi·(ei[k]-ei[k-1])+Kii·Ts·ei[k];

[0128] in,

[0129] Kpi is the current loop proportionality coefficient;

[0130] Kii is the integral coefficient of the current loop;

[0131] Dfb[k] is the duty cycle correction value for the current loop feedback.

[0132] The final recursive expression for the duty cycle is:

[0133] Dcmd[k] = Dff[k] + Dfb[k];

[0134] After limiting the final duty cycle, we get:

[0135] D[k]=clamp(Dcmd[k], Dmin, Dmax);

[0136] To further prevent abrupt changes in the BOOST duty cycle, a duty cycle slope constraint can also be added:

[0137] D[k]=D[k-1]+limit(Dcmd[k]-D[k-1],-ΔDdown,ΔDup);

[0138] in:

[0139] ΔDup is the maximum duty cycle rise step size in a single cycle;

[0140] ΔDdown is the maximum duty cycle descent step size in a single cycle.

[0141] BOOST circuit process output recursive expression

[0142] It should be noted that, in order to fully describe "how the duty cycle affects the bus voltage output", this application introduces the BOOST average model for further explanation.

[0143] The recursive expression for the inductor current of a synchronous rectified booster is:

[0144] IL[k+1]=IL[k]+Ts / L·{Vin[k]-(1-D[k])·Vbus[k]-rL·IL[k]};

[0145] in,

[0146] L stands for BOOST inductor;

[0147] rL is the equivalent resistance of the inductor;

[0148] IL[k] is the BOOST inductor current in the kth period.

[0149] The recursive expression for the DC bus voltage process output is:

[0150] Vbus[k+1]=Vbus[k]+Ts / Cbus·{(1-D[k])·IL[k]-Iload[k]};

[0151] in:

[0152] Cbus is the bus capacitor;

[0153] Iload[k] is the equivalent load current absorbed by the compressor inverter from the DC bus.

[0154] The equivalent load current of the compressor can be written as:

[0155] Iload[k] = Pcomp[k] / Vbus[k];

[0156] The compressor power can be approximated as:

[0157] Pcomp[k]=Kt·ω_f[k]·Iq_f[k]+Ploss[k];

[0158] Therefore, the bus voltage output recursive formula can be further written as:

[0159] Vbus[k+1]=Vbus[k]+Ts / Cbus·{(1-D[k])·IL[k]-[Kt·ω_f[k]·Iq_f[k]+Ploss[k]] / Vbus[k]};

[0160] This formula clearly demonstrates:

[0161] The duty cycle D[k] output by the control chip changes the inductor current and bus charging current through synchronous rectification BOOST, thereby recursively adjusting the DC bus voltage Vbus[k+1] of the next cycle.

[0162] It should be noted that in traditional dual-loop control, the outer voltage loop adjusts the current reference value based on the bus voltage deviation. When the compressor load changes abruptly (such as a speed command jump or a sudden increase in refrigeration load), the change in load current (i.e., the quadrature-axis current in this application) first causes fluctuations in the bus voltage. Only after the outer voltage loop detects the bus voltage deviation can it adjust the current reference value. The entire adjustment path is "load change → bus voltage change → outer voltage loop → inner current loop → duty cycle correction". The signal path is long and has inherent delays, so the bus voltage inevitably drops.

[0163] In this application, the inductor current reference value is obtained by superimposing the feedback adjustment amount and the feedforward compensation amount. The feedback adjustment amount is generated based on the bus voltage error through proportional-integral calculation and is used to eliminate steady-state voltage deviation. The feedforward compensation amount is generated based on the compressor power change and is used to adjust the current reference value in advance when the load changes. Specifically, the compressor load change is directly reflected in the compressor power through changes in speed and quadrature-axis current. The feedforward method directly introduces the compressor power change ΔPcomp[k] into the reference value calculation of the inner current loop. This signal does not pass through the outer voltage loop, is not limited by the response speed of the voltage loop, and is independent of the feedback adjustment path of the outer voltage loop. When the load changes, the inner current loop obtains the feedforward adjustment signal before the bus voltage shows a significant deviation, and adjusts the inductor current in advance so that the energy output of the BOOST circuit changes synchronously with the compressor load demand.

[0164] Through the above methods, this application achieves rapid compensation response of bus voltage when load changes suddenly occur, improves the defect of pure feedback structure that requires waiting for bus voltage to drop before responding to load changes, and enhances the dynamic response performance of the system.

[0165] Step 106: Output the final duty cycle command to the power switch of the BOOST circuit to control the BOOST circuit to boost the vehicle input voltage to the target bus voltage value.

[0166] In this embodiment, the final duty cycle command is used to drive the power switch of the BOOST circuit. The relationship between the output voltage Vbus of the BOOST circuit, the input voltage Vin, and the duty cycle D is Vbus = Vin / (1-D). When it is necessary to raise the bus voltage to the target value Vbus*, the controller calculates the corresponding duty cycle command according to this relationship and outputs it to the power switch. By controlling the conduction time (i.e., duty cycle) of the switch, the inductor energy storage and release process of the BOOST circuit is adjusted, thereby enabling the bus voltage to track the target bus voltage value.

[0167] This application also provides a vehicle-mounted refrigerator compressor control device, including:

[0168] BOOST circuit, including power switching transistors;

[0169] Voltage sampling circuit, used to collect bus voltage and vehicle input voltage;

[0170] Current sampling circuit, used to collect inductor current;

[0171] Back EMF observer is used to estimate compressor speed and peak back EMF in real time;

[0172] A processor is used to execute the aforementioned vehicle-mounted refrigerator compressor control method.

[0173] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. In particular, it should be noted that any modifications, equivalent substitutions, or improvements made by those skilled in the art within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for controlling a vehicle-mounted refrigerator compressor, characterized in that, The method is used for a vehicle-mounted refrigerator compressor, which is powered by a BOOST circuit; the method includes: During each control cycle, the compressor speed, back EMF peak value, on-board input voltage, bus voltage, inductor current, quadrature shaft current, and stator resistance are acquired. The target bus voltage value is calculated using a dynamic modulation margin method based on the compressor speed, back EMF peak value, quadrature shaft current, and stator resistance. The dynamic modulation margin method is a control strategy that introduces a voltage margin that changes in real time with the compressor speed when calculating the target bus voltage value. Based on the target bus voltage, on-board input voltage, quadrature axis current and compressor speed, the target duty cycle is calculated using the synchronous rectification efficiency correction method. The target bus voltage value is subjected to slope limiting processing to obtain a slope-limited bus voltage setpoint. Based on the given value of the bus voltage after the slope limitation, the bus voltage, the inductor current and the target duty cycle, the final duty cycle command is obtained through the feedforward method. The final duty cycle command is output to the power switch of the BOOST circuit to control the BOOST circuit to boost the vehicle input voltage to the target bus voltage value.

2. The method according to claim 1, characterized in that, The step of calculating the target bus voltage value using the dynamic modulation margin method based on the rotational speed and the peak value of the back electromotive force includes: The target bus voltage value is obtained by adding the back EMF utilization term, the current loop voltage drop compensation term, and the dynamic modulation margin; the dynamic modulation margin is a nonlinear function dynamically adjusted based on the compressor speed, speed change rate, quadrature shaft current, and on-board input voltage of the current control cycle; the back EMF utilization term is calculated from the back EMF peak value; the current loop voltage drop compensation term is calculated from the quadrature shaft current and stator resistance; the speed change rate is the difference between the compressor speed of the current control cycle and the compressor speed of the previous control cycle divided by the control cycle duration.

3. The method according to claim 2, characterized in that, The target bus voltage value is constrained by the upper and lower limits using the clamp function.

4. The method according to claim 1, characterized in that, Based on the target bus voltage, on-board input voltage, quadrature-axis current, and compressor speed, the target duty cycle is calculated using a synchronous rectification efficiency correction method, including: The synchronous rectification efficiency correction method is a control strategy that introduces an efficiency correction factor that dynamically changes with the compressor speed and cross-axis current. The target duty cycle is calculated from the target bus voltage, the on-board input voltage, and the synchronous rectification efficiency correction factor; the synchronous rectification efficiency correction factor is a function of the compressor speed and the quadrature shaft current.

5. The method according to claim 4, characterized in that, The synchronous rectification efficiency correction factor is constrained by the upper and lower limits using the clamp function.

6. The method according to claim 1, characterized in that, Based on the given bus voltage after slope limitation, bus voltage, inductor current, and target duty cycle, the final duty cycle command is obtained through a feedforward method, including: Based on the deviation between the given bus voltage after slope limitation and the bus voltage, the inductor current reference value is calculated using the feedforward method. The duty cycle correction is calculated based on the deviation between the inductor current reference value and the inductor current. The final duty cycle command is obtained based on the target duty cycle and the duty cycle correction amount.

7. The method according to claim 6, characterized in that, The control voltage outer loop calculates the inductor current reference value using a feedforward method based on the deviation between the given bus voltage value after slope limitation and the bus voltage, including: The feedforward method is a control strategy that adjusts the inductor current reference value in advance based on changes in compressor power. The bus voltage error is calculated based on the given bus voltage value after the slope limitation and the bus voltage itself. Obtain the compressor power feedforward; The inductor current reference value is calculated based on the bus voltage error and the compressor power feedforward.

8. The method according to claim 7, characterized in that, The acquisition of the compressor power feedforward includes: Calculate the current power of the compressor based on the rotational speed and the cross-axis current; The difference between the current power of the compressor and the compressor power in the previous control cycle is used as the power feedforward.

9. The method according to claim 1, characterized in that, The step of performing slope limiting processing on the target bus voltage value to obtain a slope-limited bus voltage setpoint includes: The bus voltage difference is calculated based on the target bus voltage value and the bus voltage of the previous control cycle. When the bus voltage difference is greater than the preset maximum voltage rise step size in a single cycle, the bus voltage setpoint is set to the sum of the bus voltage in the previous control cycle and the rise step size. When the bus voltage difference is less than the negative value of the preset maximum voltage drop step size in a single cycle, the bus voltage setpoint is set to the difference between the bus voltage in the previous control cycle and the drop step size. When the bus voltage difference is between the negative value of the falling step and the rising step, the bus voltage setpoint is set to the target bus voltage value.

10. A vehicle-mounted refrigerator compressor control device, characterized in that, include: BOOST circuit, including power switching transistors; Voltage sampling circuit, used to collect bus voltage and vehicle input voltage; Current sampling circuit, used to collect inductor current; Back EMF observer is used to estimate compressor speed and peak back EMF in real time; A processor for executing the vehicle refrigerator compressor control method as described in any one of claims 1-9.

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