High-temperature heat pump unit electric control heat dissipation system and collaborative control method

Abstract

The application discloses a high-temperature heat pump unit electric control heat dissipation system and a collaborative control method. The system comprises a main circulation loop and an auxiliary cooling branch for electric control cooling. The main circulation loop comprises an evaporator, a centrifugal compressor, a condenser and a flash economizer. The auxiliary branch takes liquid from the main circulation through a heat exchanger, and uses low-temperature refrigerant after deep throttling to cool the motor and the frequency converter. The control method collects real-time temperature, pressure and other operating parameters, calculates the thermal risk index of the motor and the frequency converter, predicts the heat dissipation load based on the compressor power, and dynamically distributes the refrigerant to each cooling branch after correction. The application comprehensively considers temperature deviation and temperature rise rate, introduces a thermal risk index to real-time correct the heat dissipation load, and dynamically distributes the cooling liquid flow according to the corrected load, so as to realize accurate response to the heat dissipation demand of the motor and the frequency converter, and avoid the overcooling or undercooling problem of the traditional fixed-flow cooling.

Description

Technical Field

[0001] This invention relates to the field of thermal management technology for high-temperature heat pump units, specifically to an electronically controlled heat dissipation system and a collaborative control method for high-temperature heat pump units. Background Technology

[0002] When a 500kW-class high-temperature heat pump unit operates at an outlet water temperature of 85-95℃, the condensing temperature reaches 95-105℃ (R245fa corresponds to a condensing pressure of approximately 900-1150 kPa), the pressure ratio reaches 5-7, and the centrifugal compressor motor input power is approximately 130-160 kW. Motor winding losses are estimated at 3-5%, approximately 4-8 kW, and inverter power module losses are estimated at 2-3%, approximately 2.5-5 kW. When the ambient temperature is above 35℃ and the unit operates continuously for more than 8 hours, the motor temperature T1 easily exceeds 135℃, and the inverter temperature T2 easily exceeds 85℃, triggering protective frequency reduction or even shutdown.

[0003] Traditional air-cooled heat dissipation solutions can only provide a temperature difference of 20-30°C under high-temperature conditions. For motor cooling loads in the range of 4-8 kW, the required air-cooled heat exchange area is too large, and the fan noise and energy consumption are significantly increased. Independent water-cooled solutions require additional configuration of circulating water pumps (approximately 1.5-3 kW), expansion tanks, independent plate heat exchangers, and piping systems, resulting in an increase in unit cost of 15-25%, larger installation size, and increased maintenance frequency.

[0004] In the scheme of directly drawing liquid from the condenser outlet for cooling, the saturation temperature of R245fa at a condensing pressure of 1000 kPa is about 98 ℃. After supercooling, the liquid temperature is still 85-92 ℃, and the temperature difference between it and the motor winding temperature (110-135 ℃) is only 20-40 ℃. There is even an inverse temperature difference between it and the frequency converter (70-85 ℃), which cannot effectively cool the frequency converter. Summary of the Invention

[0005] Technical objective: To address the shortcomings of existing high-temperature heat pump unit electrical control equipment cooling, this invention discloses a high-temperature heat pump unit electrical control heat dissipation system and a collaborative control method.

[0006] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] A high-temperature heat pump unit's electrically controlled cooling system includes a main circulation loop and an auxiliary cooling branch for electrically controlled cooling. The main circulation loop includes an evaporator, a centrifugal compressor, a condenser, a first throttling valve, a flash economizer, and a second throttling valve connected in sequence, with the outlet of the second throttling valve connected to the evaporator. The auxiliary cooling branch includes a heat exchanger, with its hot-side inlet connected to the condenser outlet and its cold-side inlet connected to the flash economizer outlet. The cold-side outlet of the heat exchanger directly returns to the low-pressure side of the main circulation loop. The coolant at the hot-side outlet of the heat exchanger undergoes electrically controlled cooling and then returns to the low-pressure side of the main circulation loop. The low-pressure side of the main circulation loop is the pipeline between the evaporator outlet and the centrifugal compressor suction port.

[0008] A third throttling valve is installed at the cold side inlet of the heat exchanger. The refrigerant drawn from the flash economizer is throttled to 180-250 kPa by the third throttling valve before entering the heat exchanger.

[0009] The electronically controlled heat dissipation system is also equipped with a controller for system operation control, and the controller is connected to the sensors and valves of the electronically controlled heat dissipation system via electrical signals.

[0010] This invention discloses a collaborative control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit, comprising the following steps:

[0011] S01. Collect the operating parameters of the high-temperature heat pump unit's electronic control heat dissipation system according to a fixed sampling period Ts. The operating parameters include the motor winding temperature T1, the inverter IGBT substrate temperature T2, the heat exchanger hot side outlet temperature T3, the condensing pressure P1, the evaporating pressure P2, the evaporator outlet superheat SH, the flash economizer liquid level Le, the centrifugal compressor operating frequency F, and the centrifugal compressor input power W.

[0012] S02. Calculate the motor thermal risk index Rm and the inverter thermal risk index Ri based on the operating parameters;

[0013] Rm = w1 * (T1 - T1_set) / (T1_max - T1_set) + w2 * (dT1 / dt) / RT1_ref;

[0014] Ri = w1 * (T2 - T2_set) / (T2_max - T2_set) + w2 * (dT2 / dt) / RT2_ref;

[0015] Where: T1_set is the target value for motor temperature control; T1_max is the upper limit for motor temperature protection; T2_set is the target value for inverter temperature control; T2_max is the upper limit for inverter temperature protection; w1 is the temperature deviation weight; w2 is the temperature rise rate weight, w1 + w2 = 1; dT1 / dt is the motor temperature change rate, in °C / s, calculated by the difference between two adjacent cycles: dT1 / dt = (T1(k) - T1(k-1)) / Ts; dT2 / dt is the inverter temperature change rate, in °C / s, dT2 / dt = (T2(k) – T2(k-1)) / Ts, k represents the current cycle number, RT1_ref is the reference value for motor temperature rise rate, and RT2_ref is the reference value for inverter temperature rise rate.

[0016] S03. Predict the heat dissipation load of the motor and the heat dissipation load of the frequency converter based on the compressor input power W, and correct the corresponding heat load based on the heat risk index by setting a correction coefficient.

[0017] S04. Calculate the refrigerant distribution requirement at the hot side outlet of the heat exchanger based on the heat exchanger's heat exchange capacity and the corrected heat dissipation load of the motor and the frequency converter, and cool the motor and the frequency converter.

[0018] Preferably, in step S03 of the present invention, the predicted motor heat dissipation load Qm_loss = km × W, and the predicted inverter heat dissipation load Qi_loss = ki × W, where km is the motor heat loss ratio coefficient and ki is the inverter heat loss ratio coefficient.

[0019] Preferably, the motor heat dissipation load Qm = Qm_loss × (1 + Km_risk × Rm) and the frequency converter heat dissipation load Qi = Qi_loss × (1 + Ki_risk × Ri) are corrected based on the thermal risk index of the present invention, where Km_risk is the motor risk amplification factor with a value of 1.5 and Ki_risk is the frequency converter risk amplification factor with a value of 1.5.

[0020] 5. The coordinated control method of the high-temperature heat pump unit's electronic control heat dissipation system according to claim 4, characterized in that, in step S04, the opening degree of the third throttle valve is adjusted to control the outlet temperature of the heat exchanger's hot side coolant according to the corrected motor heat dissipation load and inverter heat dissipation load, and the coolant at the outlet of the heat exchanger's hot side is distributed, with the refrigerant flow rate ratio λ_m = Qm / (Qm + Qi) entering the motor cooling branch and the refrigerant flow rate ratio λ_i = Qi / (Qm + Qi) entering the inverter cooling branch.

[0021] Preferably, when the auxiliary cooling branch performs electronically controlled cooling and heat dissipation, the present invention sets the following protection constraints for the main circulation loop: SH≤SH_max, where SH_max is the maximum limit value of superheat at the evaporator outlet; Le≥Le_min, where Le_min is the minimum liquid level of the flash economizer; P2≥P2_min, where P2_min is the minimum evaporation pressure of the evaporator; eta≤eta_max, where eta is the flow rate ratio of the auxiliary cooling branch and eta_max is the maximum flow rate ratio of the auxiliary branch. When the protection constraints of the main circulation loop are met, the third throttle valve is opened according to the flow rate requirement of the auxiliary cooling branch. If any protection constraint is not met, the opening degree of the third throttle valve is limited to increase and is reduced by 20% according to the current opening degree ratio. When the protection constraints are not met for more than 60 seconds, a compressor frequency reduction command is output, where the compressor target frequency F_target = F_current * 0.85, where F_current is the current frequency of the compressor.

[0022] Preferably, when adjusting the opening of the third throttle valve and the distribution of coolant at the hot side outlet of the heat exchanger, the present invention adopts a time-sequenced output strategy: first, the third throttle valve is opened to the target opening, and based on the steady-state evaporation time established on the cold side of the heat exchanger, the change in the heat exchanger outlet temperature T3 during this time is detected. If T3 is stable within the target range, the regulating valves controlling the flow into the motor cooling branch and the inverter cooling branch at the hot side outlet of the heat exchanger are adjusted to the target opening accordingly; if T3 is not stable within the target range, valve abnormalities or heat exchanger abnormalities are identified based on the changes in T3.

[0023] Preferably, in each sampling period Ts, the present invention performs heat load correction and adjustment based on the measured values ​​of motor winding temperature T1 and inverter IGBT substrate temperature T2 and the predicted value of cooling, and corrects the heat exchanger unit temperature heat exchange UA based on the measured value and the predicted value of heat exchanger outlet temperature T3.

[0024] Motor winding error e_m(k) = T1_actual(k) - T1_pred(k);

[0025] The temperature error of the IGBT substrate of the frequency converter is e_i(k) = T2_actual(k) - T2_pred(k);

[0026] The heat exchanger hot-side outlet temperature error e_hex(k) = T3_actual(k) - T3_pred(k);

[0027] Where, T1_pred(k)=T1(k-1)+Ts*(Qm_loss-Qm_actual) / Cth_motor, Cth_motor is the heat capacity of the motor windings and core; Qm_actual is the actual heat power carried away by the motor cooling branch, in W;

[0028] Qm_actual=cp_c·ṁ_m·(Tc_out,m−Tc_in,m), where: cp_c is the specific heat capacity of the refrigerant at constant pressure, in J / (kg·℃); ṁ_m is the mass flow rate of the refrigerant in the motor cooling branch, in kg / s; Tc_out,m is the outlet temperature of the refrigerant in the motor cooling branch, in ℃; Tc_in,m is the inlet temperature of the refrigerant in the motor cooling branch, in ℃;

[0029] T2_pred(k)=T2(k−1)+Ts·(Qi_loss−Qi_actual) / Cth_inv;

[0030] Where: Qi_actual is the actual heat power carried away by the inverter cooling branch, in W; Qi_actual=cp_c·ṁ_i·(Tc_out,i−Tc_in,i), ṁ_i is the refrigerant mass flow rate of the motor cooling branch, in kg / s; Cth_inv is the heat capacity of the IGBT module and substrate, in J / ℃; Tc_out,i is the refrigerant outlet temperature of the inverter cooling branch, in ℃; Tc_in,i is the refrigerant inlet temperature of the inverter cooling branch;

[0031] Heat exchanger hot-side outlet temperature prediction:

[0032] T3_pred(k) = Th_in − Qhex_actual / (cp_h·ṁ_h), where Qhex_actual is the actual heat exchange of the heat exchanger in W, cp_h is the isobaric specific heat capacity of the hot-side fluid in the heat exchanger in J / (kg·℃), ṁ_h is the mass flow rate of the hot-side fluid in the heat exchanger in kg / s, and Th_in is the inlet temperature of the hot-side fluid in the heat exchanger in ℃.

[0033] Based on the calculated e_m(k), e_i(k), and e_hex(k), Km_risk, Ki_risk, and UA corrections are performed, where UA is the heat exchanger's heat transfer per unit temperature.

[0034] If |e_m(k)| is greater than 3℃ for 3 consecutive periods: Km_risk = Km_risk + 0.1 * sign(e_m); and the error is recalculated using the adjusted period as the starting period, with the following limit: 0.5 ≤ Km_risk ≤ 3.0;

[0035] If |e_i(k)| is greater than 3℃ for 3 consecutive periods, Ki_risk = Ki_risk + 0.1*sign(e_i), and the error is recalculated using the adjusted period as the starting period. The limit is: 0.5 ≤ Ki_risk ≤ 3.0.

[0036] If |e_hex(k)| is greater than 5 ℃ for 3 consecutive cycles, then UA_new = UA_old * (Qhex_actual / Qhex_target)

[0037] Qhex_target is the heat exchange required to reach the target outlet temperature; when the measured heat exchange is lower than the target heat exchange, this ratio is less than 1, and UA_new decreases accordingly; the limit range is: 0.6 ≤ UA_new / UA_rated ≤ 1.2, where UA_rated is the calibrated heat exchanger heat exchange per unit temperature. When UA drops below 60% of the calibrated value, a heat exchanger dirt blockage alarm is triggered.

[0038] Preferably, the present invention performs the following four levels of fault diagnosis sequentially on the high-temperature heat pump unit in each sampling cycle:

[0039] D1: Sensor data consistency diagnosis:

[0040] The consistency rule is: T3≤T1, T3<Th_in,T2≥T_ambient,P1> P2, where Th_in is the heat exchanger hot-side inlet temperature and T_ambient is the ambient temperature;

[0041] The fault sensor localization method combines multi-rule cross-voting with trend verification: each sensor participates in multiple consistency rules, the number of rules violated for each sensor is counted, and the sensor with the most violated rules is identified as the source of the anomaly; and the anomaly is confirmed by combining the change rate verification of the sensor's own historical sequence and the trend consistency verification with the associated quantities.

[0042] If a sensor is identified as abnormal and this condition persists for three consecutive sampling cycles, the corresponding sensor is marked as abnormal, and the sensor enters degradation mode.

[0043] For T1 anomalies: replace with estimated values, T1_est = T1_base + km·W / Cth_motor·t_run, where t_run is the cumulative running time since this startup, and T1_base is the initial temperature at startup;

[0044] For the T2 exception: replace it with an estimated value, T2_est = T2_base + ki·W / Cth_inv·t_run;

[0045] For T3 anomaly: Estimate T3 by referring to the table based on the opening of the third throttle valve and the condensing pressure P1. At the same time, limit the valve opening um of the motor cooling branch and the valve opening ui of the inverter cooling branch to no more than 50%, and output a sensor fault alarm signal.

[0046] For P1 or P2 anomalies: Replace with compressor frequency F and thermodynamic model estimated value, P1_est = f_high(F, Th_in), P2_est = f_low(F, T_evap), enter pressure sensor degradation mode, limit compressor frequency F to no more than 85% of the current value, and output pressure sensor fault alarm signal;

[0047] D2: Valve Response Normality Diagnosis:

[0048] The response judgment rule is as follows: output the valve opening adjustment amount, collect the corresponding temperature change caused by the valve opening adjustment within the sampling period, and mark the corresponding valve abnormality when the temperature does not change, the direction of change is opposite to the expectation, or the change amount is less than γ times the expected amount. γ is the response effectiveness coefficient, which is 0.3~0.5.

[0049] After a valve response is marked as abnormal, the valve enters a degraded mode: the opening of the abnormal valve is fixed at the current value and no longer adjusted, the cooling regulation is handled by the other movable valves, the compressor frequency F is limited to no more than 80% of the current value, and a valve fault alarm signal is output.

[0050] D3: Diagnosis of heat exchanger heat exchange capacity adequacy:

[0051] When the electronically controlled cooling demand naturally drives the third throttle valve opening u3 to ≥ 95%, the heat exchange capacity is evaluated, and a three-state determination is adopted:

[0052] u3<95%: The heat exchange capacity is not fully utilized, and it is judged as "not evaluated". The previous valid diagnosis is retained, and the heat exchanger is not assumed to be normal.

[0053] u3≥95% and T3 meets the standard: the heat exchange capacity is deemed sufficient;

[0054] If u3≥95% AND T3>T3_target+10℃ and this condition persists for more than 5 consecutive sampling cycles, then the heat exchanger is deemed to have insufficient heat exchange capacity.

[0055] At this time, maintain maximum cold source supply, u3=100%, correct UA value online, reduce the temperature target of electronic cooling, increase control temperature, limit compressor frequency F to not exceed 90% of the current value, and output heat exchanger maintenance alarm signal;

[0056] D4: Serious over-temperature diagnosis of motor or inverter. Set the upper limit of motor winding temperature T1 and inverter IGBT substrate temperature T2. When the limit is exceeded, perform emergency shutdown protection. Shutdown protection process: immediately close the motor cooling regulating valve and inverter cooling regulating valve, close the third throttle valve, and output the compressor shutdown command.

[0057] If the D4 level severe over-temperature shutdown protection is triggered three times consecutively, or if two or more sensors and valves malfunction simultaneously, the safety shutdown procedure will be executed.

[0058] Preferably, the controller of the present invention solves the following objective function in each cycle to determine the optimal values ​​of u3, um, and ui:

[0059] minJ=w_T*[(T1-T1_set) / (T1_max-T1_set)]^2+[(T2-T2_set) / (T2_max-T2_set)]^2+w_E*(Maux / Mmain)^2+w _S*[max(0,SH-SH_max) / SH_max]^2+w_L*[max(0,Le_min-Le) / Le_min]^2+w_P*[max(0,P2_min-P2) / P2_min]^2

[0060] Constraints: 0 ≤ u3 ≤ 100%, 0 ≤ um ≤ 100%, 0 ≤ ui ≤ 100%; Max / Mmain ≤ eta_max;

[0061] Weighting coefficient values: w_T=1.0; w_E=0.4; w_S=8.0; w_L=8.0; w_P=8.0.

[0062] Beneficial effects: The present invention has the following beneficial effects:

[0063] 1. This invention comprehensively considers temperature deviation and temperature rise rate, introduces a thermal risk index to correct the heat dissipation load in real time, and dynamically allocates coolant flow rate according to the corrected load, thereby achieving a precise response to the heat dissipation needs of motors and frequency converters and avoiding the overcooling or undercooling problems of traditional constant flow cooling.

[0064] 2. This invention introduces a main circulation protection constraint in the auxiliary cooling branch control to ensure that the electronically controlled cooling does not sacrifice the performance of the main circulation, thus achieving synergistic optimization of heat dissipation and cooling energy efficiency.

[0065] 3. Based on the deviation between the measured temperature and the model prediction, the system can correct the risk amplification factor and the heat exchanger UA value online, and automatically compensate for the performance deviation caused by changes in refrigerant charge, heat exchanger clogging, etc., so that the control strategy always closely matches the actual operating conditions.

[0066] 4. This invention sets up a four-level fault diagnosis and fault tolerance mechanism to cover multiple dimensions of anomalies such as sensors, valves, heat exchangers, and over-temperature. It can automatically switch to degraded mode and output alarms when a fault occurs. In the event of continuous serious faults, it can perform a safe shutdown, effectively avoiding damage to electrical control components due to overheating, and improving the operating life and safety of the unit.

[0067] 5. This invention uses a third throttling valve to deeply throttle the refrigerant drawn from the flash economizer to a low-pressure range of 180–250 kPa, so that the cold side of the heat exchanger can provide sufficient cooling capacity, ensuring effective cooling of the electronic control components even under extreme conditions such as high condensing temperature and high ambient temperature.

[0068] 6. This invention introduces an auxiliary branch flow rate ratio term into the multi-objective optimization function to minimize the auxiliary branch flow rate while meeting the electronic control cooling requirements. This reduces the impact of bypass refrigerant on the main circulation efficiency and improves the overall energy efficiency. Attached Figure Description

[0069] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0070] Figure 1 This is a schematic diagram of the overall structure of the high-temperature heat pump unit of the present invention; Figure 2 This is a flowchart of the control method of the present invention; Figure 3 This is a refrigerant distribution logic diagram for the present invention; Figure 4 This is a diagram showing the protection constraint relationship of the main loop of the present invention; Figure 5 This is a flowchart of the fault diagnosis process of the present invention;

[0071] Among them, 1-evaporator, 2-centrifugal compressor, 3-condenser, 4-flash economizer, 5a-first throttle valve, 5b-second throttle valve, 5c-third throttle valve, 6-frequency converter, 7-motor cooling chamber, 8-auxiliary plate heat exchanger, 9-controller, 10-motor cooling regulating valve, 11-frequency converter cooling regulating valve. Detailed Implementation

[0072] Reference will now be made in detail to embodiments of the present disclosure, one or more of which are set forth herein. Each embodiment and example is provided by way of explanation of the apparatus, composition, and materials of the present disclosure, and not by way of limitation. Rather, the following description provides convenient illustrations for implementing exemplary embodiments of the present disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the teachings of the present disclosure without departing from the scope or spirit of the present disclosure.

[0073] like Figure 1As shown, the high-temperature heat pump unit electronically controlled heat dissipation system provided by the present invention includes a main circulation loop and an auxiliary cooling branch for electronically controlled cooling. The main circulation loop includes an evaporator 1, a centrifugal compressor 2, a condenser 3, a first throttling valve 5a, a flash economizer 4, and a second throttling valve 5b, which are connected in sequence and via pipelines. The outlet of the second throttling valve 5b is connected to the evaporator, forming a complete refrigerant main circulation path. The auxiliary cooling branch includes a heat exchanger, which is an auxiliary plate heat exchanger 8. The heat exchanger has a hot side channel and a cold side channel. The hot side inlet of the heat exchanger is connected to the outlet of the condenser. A portion of high-temperature and high-pressure liquid refrigerant is drawn from the outlet of the condenser 3 and enters the hot side channel of the heat exchanger. The cold side inlet of the heat exchanger is connected to the outlet of the flash economizer 4 through the third throttling valve 5c. The medium-pressure liquid refrigerant drawn from the flash economizer 4 is deeply throttled by the third throttling valve 5c to a low-pressure range of 180kPa~250kPa and then enters the cold side channel of the heat exchanger. In the heat exchanger, it exchanges heat countercurrently with the high-temperature refrigerant in the hot side channel. After absorbing heat, it evaporates into gaseous refrigerant. The cold side outlet of the heat exchanger directly returns to the low-pressure side of the main circulation loop. The low-pressure side of the main circulation loop is the pipeline between the outlet of the evaporator and the suction port of the centrifugal compressor. The coolant (i.e., the cooled high-pressure liquid refrigerant) from the hot side outlet of the heat exchanger flows sequentially through the motor cooling branch and the inverter cooling branch. The motor cooling branch is connected to the motor cooling chamber 7 and is equipped with a motor cooling regulating valve 10. The inverter cooling branch is connected to the inverter and is equipped with an inverter cooling regulating valve 11. The coolant is distributed by controlling the valve opening to cool and dissipate heat from the motor windings and the inverter IGBT substrate, and then flows back to the low-pressure side of the main circulation loop. The electronically controlled heat dissipation system also includes a controller 9. The controller is electrically connected to the temperature sensor, pressure sensor, liquid level sensor, and each regulating valve in the electronically controlled heat dissipation system to collect operating parameters and output valve control commands.

[0074] In an embodiment of the present invention, under a heating capacity of 500kW, the total mass flow rate of the main circulating R245fa refrigerant Mmain is approximately 2.8-3.5 kg / s (calculated based on an evaporation temperature of 40 ℃ and a condensation temperature of 98 ℃), the evaporation pressure P2 is approximately 250 kPa, and the condensation pressure P1 is approximately 1000 kPa.

[0075] A high-temperature R245fa refrigerant (temperature approximately 88-92 ℃, pressure approximately 1000 kPa) is drawn from the high-pressure liquid refrigerant pipeline between the outlet of condenser 3 and the first throttling valve 5a, and enters the hot-side heat exchange channel of auxiliary plate heat exchanger 8. A liquid R245fa refrigerant (temperature approximately 55-60 ℃, pressure approximately 500 kPa) is drawn from the liquid outlet of flash economizer 4 and the second throttling valve 5b, and after being deeply throttled by the third throttling valve 5c to approximately 180-250 kPa, it enters the cold-side heat exchange channel of auxiliary plate heat exchanger 8. R245fa has a saturation temperature of approximately 28 ℃ at 180 kPa and approximately 40 ℃ at 250 kPa. Therefore, a low-temperature evaporation environment of 28-40 ℃ can be formed on the cold side, establishing a heat exchange temperature difference of approximately 50-60 ℃ between it and the high-temperature refrigerant of 88-92 ℃ on the hot side.

[0076] The gaseous or gas-liquid two-phase R245fa refrigerant at the cold side outlet of the auxiliary plate heat exchanger 8 is reconnected to the low-pressure side of the main circulation.

[0077] After cooling, the R245fa liquid refrigerant (temperature reduced to 30-45℃) at the hot side outlet of the auxiliary plate heat exchanger 8 is divided into two paths: one path enters the compressor motor cooling chamber via the motor cooling regulating valve 10, using the 30-45℃ refrigerant to cool the 110-130℃ motor windings (temperature difference 65-100℃, sufficient heat exchange driving force); the other path enters the inverter 6 heat dissipation channel via the inverter cooling regulating valve 11, using the 30-45℃ refrigerant to cool the 65-85℃ inverter power module (temperature difference 20-55℃). Both refrigerants return to the low-pressure side after absorbing heat.

[0078] Controller 9 is connected to the following sensors and signal sources:

[0079] Motor temperature sensor: Pt100 platinum resistance thermometer, measures motor winding temperature T1, range 0-200 ℃, accuracy + / -0.5℃.

[0080] Inverter temperature sensor: NTC thermistor, measures the temperature T2 of the inverter's IGBT substrate, range 0-150 ℃, accuracy + / - 1 ℃.

[0081] Auxiliary plate heat exchanger hot-side outlet temperature sensor: Pt100, measuring T3, range 0-150 ℃

[0082] Condensation pressure sensor: Piezoresistive type, measures P1, range 0-2000 kPa, accuracy + / -0.5%FS

[0083] Evaporation pressure sensor: Piezoresistive type, measures P2, range 0-1000 kPa, accuracy + / -0.5%FS

[0084] Evaporator outlet superheat: SH is calculated from the difference between the evaporator outlet temperature sensor and the saturation temperature corresponding to P2.

[0085] Flash economizer level sensor: float type or differential pressure type, measures Le, range 0-100%.

[0086] Compressor operating frequency F: Read the inverter output frequency from the inverter 6 communication interface (Modbus RTU protocol), in Hz. Centrifugal compressor 2 uses a 2-pole high-speed permanent magnet synchronous motor with a speed n = 60 * F. The rated frequency of 350 Hz corresponds to a rated speed of 21000 r / min, and the operating frequency range is 150-400 Hz.

[0087] Compressor input power W: Real-time input power read from the inverter 6 communication interface, in kW, with a rated value of approximately 145kW.

[0088] The controller 9 internally executes six core functions sequentially: data filtering, status identification, heat load prediction, cooling capacity calculation, constraint optimization, and fault diagnosis. Outputs include: u3, representing the opening degree of the third throttle valve 5c (range 0-100%); um, representing the opening degree of the motor cooling regulating valve 10 (range 0-100%); ui, representing the opening degree of the inverter cooling regulating valve 11 (range 0-100%); compressor frequency reduction command; and alarm and shutdown commands.

[0089] Based on the aforementioned system, this invention also provides a collaborative control method for the electrically controlled cooling system of a high-temperature heat pump unit. This method involves a controller that automatically operates according to a set sampling period and execution logic. The controller collects operating parameters of the electrically controlled cooling system of the high-temperature heat pump unit according to a fixed sampling period Ts of 20 seconds. These operating parameters include the motor winding temperature T1, the inverter IGBT substrate temperature T2, the heat exchanger hot-side outlet temperature T3, the condensing pressure P1, the evaporating pressure P2, the evaporator outlet superheat SH, the flash economizer level Le, the centrifugal compressor operating frequency F, and the centrifugal compressor input power W. These collected parameters are sent to the controller's internal calculation unit for subsequent risk assessment and valve control.

[0090] After data acquisition, filtering is performed. This invention applies a first-order exponentially weighted low-pass filter to each acquisition channel:

[0091] X_f(k) = alpha * X_f(k-1) + (1 - alpha) * X_raw(k);

[0092] Where: X_f(k) -- the filtered output value of the kth sampling period;

[0093] X_f(k-1) -- The filtered output value of the (k-1)th sampling period;

[0094] X_raw(k) -- The original sampled value of the kth sampling period;

[0095] alpha -- filter coefficient, set to 0.85

[0096] k -- sampling number, k = 1, 2, 3, ...

[0097] The filtering time constant tau = -Ts / ln(alpha) = -20 / ln(0.85) = 123 seconds

[0098] This time constant matches the thermal time constant of the inverter's heat sink (approximately 60-120 seconds), effectively filtering out sensor noise without excessively smoothing out the actual temperature rise trend.

[0099] Based on the filtered P1, the condensation temperature Tc is obtained from the R245fa saturation temperature table. Combined with F, the operating range is determined.

[0100] Low load: F < 200 Hz (speed < 12000 r / min), W < 60 kW

[0101] Medium load: 200 Hz <= F < 300 Hz, 60 kW <= W < 110 kW

[0102] High load: F >= 300 Hz (speed >= 18000 r / min), W >= 110 kW

[0103] After the parameters are collected, the controller calculates the motor thermal risk index Rm and the inverter thermal risk index Ri based on the operating parameters.

[0104] Specifically, the motor thermal risk index Rm is calculated according to the following formula: Rm = w1 * (T1 - T1_set) / (T1_max - T1_set) + w2 * (dT1 / dt) / RT1_ref; the inverter thermal risk index Ri is calculated according to the following formula: Ri = w1 *(T2 - T2_set) / (T2_max - T2_set) + w2 * (dT2 / dt) / RT2_ref. Where T1_set is the target value for motor temperature control, T1_max is the upper limit for motor temperature protection, T2_set is the target value for inverter temperature control, T2_max is the upper limit for inverter temperature protection, w1 is the temperature deviation weight, and w2 is the temperature rise rate weight, satisfying w1 + w2 = 1. In this embodiment, w1 is taken as 0.7, and w2 is taken as 0.3. dT1 / dt is the motor temperature change rate, in °C / s, calculated from the difference between two adjacent sampling periods: dT1 / dt = (T1(k) - T1(k-1)) / Ts, where k represents the current period number; dT2 / dt is the inverter temperature change rate, in °C / s, dT2 / dt = (T2(k) – T2(k-1)) / Ts; RT1_ref is the reference value for the motor temperature rise rate, and RT2_ref is the reference value for the inverter temperature rise rate. These reference values ​​can be obtained based on the thermal characteristics calibration of the motor and inverter. For example, in this embodiment, RT1_ref is 0.5 °C / s, and RT2_ref is 0.8 °C / s. The calculated thermal risk index reflects the current thermal safety margin of the electronic control components; the closer the index is to 1, the closer it is to a dangerous state.

[0105] The controller predicts the motor heat dissipation load and inverter heat dissipation load based on the compressor input power W, and adjusts the corresponding heat loads based on the thermal risk index using correction coefficients. Specifically, the predicted motor heat dissipation load Qm_loss = km × W, and the predicted inverter heat dissipation load Qi_loss = ki × W, where km is the motor heat loss proportionality coefficient and ki is the inverter heat loss proportionality coefficient. These two coefficients can be obtained through experimental calibration. For example, in this embodiment, for a 500kW unit, the motor efficiency is approximately 95.5%, and the loss accounts for approximately 4.5% of the input power, so km is set to 0.045; the inverter efficiency is approximately 97.5%, and the loss accounts for approximately 2.5% of the input power, so ki is set to 0.025. In specific applications, these coefficients can be adjusted according to the compressor type and motor characteristics.

[0106] After obtaining the basic heat load forecast, a correction is made based on the heat risk index. The corrected motor heat dissipation load Qm = Qm_loss × (1 + Km_risk × Rm), and the corrected inverter heat dissipation load Qi = Qi_loss × (1 + Ki_risk × Ri), where Km_risk is the motor risk amplification factor with a value of 1.5, and Ki_risk is the inverter risk amplification factor with a value of 1.5. Through this correction method, when the heat risk index increases, the controller will correspondingly increase the estimated value of the heat dissipation load, thereby increasing the cooling supply in advance and achieving the effect of preventive control.

[0107] After completing the heat load correction, the controller calculates the refrigerant distribution requirement at the hot-side outlet of the heat exchanger based on the heat exchanger's heat exchange capacity and the corrected motor and inverter heat dissipation loads, and then cools the motor and inverter. Specifically, Qhex = UA * LMTD, LMTD = (dT1_hex - dT2_hex) / ln(dT1_hex / dT2_hex), where dT1_hex = Th_in - Tc_out represents the temperature difference between the hot-side inlet and cold-side outlet, dT2_hex = Th_out - Tc_in represents the temperature difference between the hot-side outlet and cold-side inlet, Th_in is the hot-side inlet temperature = condenser outlet subcooled liquid temperature, approximately 90 ℃, Th_out represents the hot-side outlet temperature, equal to the auxiliary plate heat exchanger hot-side outlet temperature T3; Tc_in The cold-side inlet temperature is equal to the saturation temperature of R245fa after throttling by the third throttling valve (5c); Tc_out represents the cold-side outlet temperature, equal to the outlet temperature after cold-side evaporation; Qhex represents the actual heat transfer capacity of the auxiliary plate heat exchanger in kW; UA represents the heat transfer capacity per unit temperature of the heat exchanger, calculated by multiplying the overall heat transfer coefficient of the auxiliary plate heat exchanger by its area. For example, if a brazed plate heat exchanger is selected, the heat transfer area is approximately 2.5 m². 2 The overall heat transfer coefficient is approximately 480 W / (m²). 2 *℃), UA = 480*2.5 / 1000 = 1.2 kW / ℃).

[0108] Based on the corrected motor and inverter heat dissipation loads, the controller first adjusts the opening of the third throttle valve to control the outlet temperature of the hot-side coolant in the heat exchanger. Then, it distributes the coolant flow rate into the hot-side outlet of the heat exchanger. The proportion of refrigerant flow rate entering the motor cooling branch is λ_m = Qm / (Qm + Qi), and the proportion entering the inverter cooling branch is λ_i = Qi / (Qm + Qi). If Qhex is still less than Qc = Qm + Qi when u3 = 100%, the auxiliary plate heat exchanger is deemed to have insufficient heat exchange capacity, triggering a degradation strategy. Total refrigerant flow rate in the auxiliary branch:

[0109] Maux = Qc / delta_h_cool, where delta_h_cool is the enthalpy change of the refrigerant in the cooling channel, in kJ / kg; the target flow rate of the motor branch Mm = λ_m * Maux = Qm / delta_h_cool, and the target flow rate of the inverter branch Mi = λ_i * Maux = Qi / delta_h_cool.

[0110] The controller controls the opening of the motor cooling regulating valve 10 at the inlet of the motor cooling branch and the opening of the inverter cooling regulating valve 11 to make the actual flow ratio close to the target flow ratio.

[0111] During the electronically controlled cooling and heat dissipation process of the auxiliary cooling branch, the controller simultaneously monitors the protection constraints of the main circulation loop to ensure that the operation of the auxiliary cooling branch does not adversely affect the stability and energy efficiency of the main circulation loop. The protection constraints for the main circulation loop include: SH ≤ SH_max, where SH_max is the maximum superheat limit at the evaporator outlet. In this embodiment, SH_max is set to 10℃. If SH > 10℃, it indicates insufficient liquid supply to the evaporator and excessive refrigerant extraction by the auxiliary branch; Le ≥ Le_min, where Le_min is the minimum liquid level in the flash economizer. In this embodiment, Le_min is set to 25% of the liquid level range. If Le < 25%, it indicates insufficient liquid refrigerant in the economizer, affecting the gas replenishment effect and liquid extraction by the auxiliary branch; P2 ≥ P2_min, where P2_min is the minimum evaporation pressure of the evaporator. In this embodiment, this pressure is set according to the refrigerant type. For example, R245fa has a saturation temperature of approximately 32℃ at 200kPa. A value below this indicates an excessively low evaporation temperature. The evaporator may experience frosting or deterioration in heat exchange; eta ≤ eta_max, where eta is the proportion of auxiliary cooling branch flow (i.e., the ratio of auxiliary branch flow to the total main circulation flow), and eta_max is the maximum proportion of auxiliary branch flow. In this embodiment, eta_max is 10%, and the auxiliary branch flow proportion does not exceed 10%. The controller checks the above constraints in each sampling cycle. When all protection constraints are met, the third throttle valve opens according to the flow demand of the auxiliary cooling branch. If any protection constraint is not met, the controller restricts the opening of the third throttle valve from increasing further and reduces it by 20% according to the current opening proportion, i.e., executes u3_new = u3_current × 0.8. When the protection constraints are not met for more than 60 seconds, the controller outputs a compressor frequency reduction command, with the compressor target frequency F_target = F_current × 0.85, where F_current is the current compressor frequency, to reduce the overall system load and create conditions for the recovery of the main circulation protection constraints. In one embodiment, when multiple protection constraints are violated simultaneously, the reduction ratio can be appropriately increased to 30%, and the frequency reduction amplitude can be adjusted to 0.8 times the current frequency.

[0112] When adjusting the opening of the third throttle valve and the coolant distribution at the hot-side outlet of the heat exchanger, the controller employs a time-sequential output strategy to avoid system oscillations and coupling interference caused by the simultaneous operation of multiple valves. Specifically, the controller first outputs an opening adjustment signal to the third throttle valve, opening it to the target opening. Based on the steady-state evaporation time established on the cold side of the heat exchanger (which can be estimated based on the cold-side volume and refrigerant flow rate, and is set to 60 seconds in this embodiment, i.e., 3 sampling periods), the controller detects the change in the heat exchanger outlet temperature T3 during this time period. If T3 stabilizes within the target range (e.g., within T3_target ± 2℃), the controller continues to output opening adjustment signals to the regulating valves of the motor cooling branch and the inverter cooling branch, adjusting both regulating valves to the corresponding target openings. If T3 does not stabilize within the target range, meaning T3 deviates from the target range beyond the allowable range, the controller identifies valve or heat exchanger malfunctions based on the changes in T3: If T3 remains consistently high and the third throttle valve opening has reached its upper limit, it is determined that the heat exchange capacity is insufficient or the cold-side liquid supply is abnormal. Ensure that the cold source has been established before opening the downstream branch to prevent high-temperature refrigerant (88-92 ℃) from entering the motor cooling chamber or inverter heat dissipation channel without sufficient cooling; If T3 fluctuates drastically without convergence, it is determined that the third throttle valve response is abnormal or the sensor is subject to noise interference. At this time, the controller issues an alarm signal and enters the fault diagnosis process.

[0113] To further improve control accuracy and adaptability, the controller also performs heat load correction adjustments based on the measured values ​​of the motor winding temperature T1 and the inverter IGBT substrate temperature T2, and the predicted cooling values ​​within each sampling cycle. Furthermore, it corrects the heat exchanger's heat transfer per unit temperature UA based on the measured and predicted values ​​of the heat exchanger outlet temperature T3. First, the motor winding error e_m(k) = T1_actual(k) - T1_pred(k), the inverter IGBT substrate temperature error e_i(k) = T2_actual(k) - T2_pred(k), and the heat exchanger hot-side outlet temperature error e_hex(k) = T3_actual(k) - T3_pred(k) are calculated.

[0114] Where, T1_pred(k) = T1(k-1) + Ts(Qm_loss - Qm_actual) / Cth_motor, Cth_motor is the heat capacity of the motor windings and core, in J / ℃, which can be obtained through motor design parameters or experimentally determined; Qm_actual is the actual heat power carried away by the motor cooling branch, in W, Qm_actual = cp_c·ṁ_m·(Tc_out,m−Tc_in,m), where cp_c is the specific heat capacity of the refrigerant at constant pressure, in J / (kg·℃), ṁ_m is the mass flow rate of the refrigerant in the motor cooling branch, in kg / s, and the flow characteristic through the valve at opening um is ṁ_m = ρ_c · Cv(um) · ρ_c is the refrigerant density (kg / m³), Cv(um) is the flow coefficient of motor cooling regulating valve 10 at an opening degree of um (look up from the valve characteristic curve), ΔP_m is the pressure difference across the valve in the motor cooling branch (Pa), Tc_out,m is the refrigerant outlet temperature in the motor cooling branch (°C), and Tc_in,m is the refrigerant inlet temperature in the motor cooling branch (°C).

[0115] T2_pred(k) = T2(k−1) + Ts·(Qi_loss−Qi_actual) / Cth_inv, where Qi_actual is the actual heat power carried away by the inverter cooling branch, in W; Qi_actual = cp_c·ṁ_i·(Tc_out,i−Tc_in,i), where ṁ_i is the refrigerant mass flow rate of the motor cooling branch, in kg / s; Cth_inv is the heat capacity of the IGBT module and substrate, in J / ℃; Tc_out,i is the refrigerant outlet temperature of the inverter cooling branch, in ℃; and Tc_in,i is the refrigerant inlet temperature of the inverter cooling branch.

[0116] The predicted outlet temperature of the heat exchanger is T3_pred(k) = Th_in − Qhex_actual / (cp_h·ṁ_h), where Qhex_actual is the actual heat exchange of the heat exchanger in W, cp_h is the specific heat capacity of the hot-side fluid at constant pressure in J / (kg·℃), ṁ_h is the mass flow rate of the hot-side fluid in the heat exchanger in kg / s, and Th_in is the inlet temperature of the hot-side of the heat exchanger in ℃.

[0117] After calculating the above errors, the controller performs Km_risk, Ki_risk and UA corrections based on e_m(k), e_i(k) and e_hex(k), where UA is the heat exchanger's heat exchange capacity per unit temperature, in W / ℃.

[0118] If |e_m(k)| is greater than 3℃ for 3 consecutive periods, then execute Km_risk=Km_risk+0.1sign(e_m), and recalculate the error using the adjusted period as the starting period. The limit is 0.5≤Km_risk≤3.0.

[0119] If |e_i(k)| is greater than 3℃ for 3 consecutive periods, then Ki_risk = Ki_risk + 0.1 * sign(e_i) is executed, and the error is recalculated using the adjusted period as the starting period. The limit is 0.5 ≤ Ki_risk ≤ 3.0.

[0120] If |e_hex(k)| is greater than 5℃ for three consecutive cycles, then UA_new = UA_old * (Qhex_actual / Qhex_target) is executed, where Qhex_target is the heat exchange required to reach the target outlet temperature. When the measured heat exchange is lower than the target heat exchange, this ratio is less than 1, and UA_new decreases accordingly, with a limit range of 0.6≤UA_new / UA_rated≤1.2, where UA_rated is the calibrated heat exchanger heat exchange per unit temperature. When UA drops below 60% of the calibrated value, a heat exchanger fouling alarm is triggered. The above correction process is executed independently in each sampling cycle, enabling the system to continuously optimize its control parameters over time, adapting to the effects of changes in refrigerant charge, heat exchanger scaling or fouling, and changes in environmental conditions.

[0121] In normal control mode, the controller solves the following objective function in each cycle to determine the optimal values ​​of u3, um, and ui: minJ=w_T{[(T1-T1_set) / (T1_max-T1_set)]^2+[(T2-T2_set) / (T2_max-T2_set)]^2}+w_E(Maux / Mmain)^2+w_S[max(0,SH-SH_max) / SH_max]^2+w_L[max(0,Le_min-Le) / Le_min]^2+w_P*[max(0,P2_min-P2) / P2_min]^2.

[0122] The constraints for solving this objective function are: 0 ≤ u3 ≤ 100%, 0 ≤ um ≤ 100%, 0 ≤ ui ≤ 100%, and Max / Mmain ≤ eta_max. The weighting coefficients are: w_T = 1.0, w_E = 0.4, w_S = 8.0, w_L = 8.0, and w_P = 8.0. By solving this objective function, control is performed using the optimized solution under normal control mode. However, in degraded control mode, since the optimized input is unreliable, the data before optimization using the objective function is directly used to participate in system operation control to ensure system controllability.

[0123] During each sampling cycle, the controller also performs a four-level fault diagnosis process on the high-temperature heat pump unit in sequence to improve the system's fault tolerance and operational safety.

[0124] D1 is for sensor data consistency diagnosis, and the consistency rules include: T3≤T1, T3<Th_in、T2≥T_ambient、P1> P2, where Th_in is the inlet temperature of the heat exchanger on the hot side, and T_ambient is the ambient temperature, which can be obtained by an ambient temperature sensor installed outside the unit. Fault sensor location employs a combination of multi-rule cross-voting and trend verification: each sensor participates in multiple consistency rules, the number of violated rules for each sensor is counted, and the sensor with the most violated rules is identified as the anomaly source. This is further confirmed by combining the sensor's own historical sequence change rate verification and trend consistency verification with related quantities.

[0125] If a sensor is determined to be abnormal and continues for 3 sampling cycles, the controller marks the corresponding sensor as abnormal and enters sensor degradation mode: For T1 abnormality, an estimated value is used instead, T1_est = T1_base + km·W / Cth_motor·t_run, where t_run is the cumulative running time since this start-up, and T1_base is the initial temperature at start-up; for T2 abnormality, an estimated value is used instead, T2_est = T2_base + ki·W / Cth_inv·t_run; for T3 abnormality, T3 is estimated by looking up a table based on the opening of the third throttle valve and the condensing pressure P1, while the valve opening um of the motor cooling branch and the valve opening ui of the inverter cooling branch are limited to no more than 50%, and a sensor fault alarm signal is output; for P1 or P2 abnormality, the compressor frequency F and the estimated value of the thermodynamic model are used instead, P1_est = f_high(F, Th_in), P2_est = f_low(F, T_evap), where f_high and f_low are pre-calibrated thermodynamic model functions, enters the pressure sensor degradation mode, limits the compressor frequency F to no more than 85% of the current value, and outputs a pressure sensor fault alarm signal.

[0126] D2 is for valve response normality diagnosis. The response judgment rule is as follows: after outputting the valve opening adjustment amount, the corresponding temperature change caused by the valve opening adjustment is collected within the sampling period. When the temperature does not change, the direction of change is opposite to the expectation, or less than γ times the expected change amount, the corresponding valve is marked as abnormal. γ is the response effectiveness coefficient, which is taken as 0.4 in this embodiment. For example, when the opening of the third throttle valve increases, T3 is expected to decrease. If T3 increases instead or the decrease is less than 0.4 times the expected change amount, the third throttle valve response is judged to be abnormal. When the opening of the motor branch regulating valve increases, T1 is expected to decrease. If T1 does not change or increases, the valve is judged to be abnormal. After marking the valve response as abnormal, the valve enters the valve degradation mode: the abnormal valve opening is fixed at the current value and no longer adjusted. The remaining movable valves take over the cooling regulation, the compressor frequency F is limited to no more than 80% of the current value, and a valve fault alarm signal is output.

[0127] D3 is a diagnostic test for the adequacy of the heat exchanger's heat exchange capacity. When the opening of the third throttle valve, u3, driven by the natural cooling demand of the electronic control system reaches ≥95%, a heat exchange capacity assessment is initiated, employing a three-state judgment: When u3 < 95%, the heat exchange capacity is not fully utilized, and the result is judged as "not assessed," maintaining the previous valid diagnostic conclusion and not assuming the heat exchanger is normal; when u3 ≥ 95% and T3 meets the target (i.e., T3 is within the allowable deviation range near the target temperature), the heat exchange capacity is judged to be sufficient; when u3 ≥ 95% and T3 > T3_target + 10℃ for more than 5 consecutive sampling cycles, the heat exchanger's heat exchange capacity is judged to be insufficient. In this case, the heat exchanger enters a degradation mode. The controller maintains the maximum cold source supply, i.e., keeps u3 = 100%, corrects the UA value online, lowers the temperature target of the electronic cooling system (i.e., appropriately increases T3_target to reduce the burden on the heat exchanger), limits the compressor frequency F to no more than 90% of the current value, and outputs a heat exchanger maintenance alarm signal to prompt the operator to clean or maintain the heat exchanger.

[0128] D4 is a severe over-temperature diagnosis for the motor or inverter. It sets the upper temperature limits for the motor winding temperature T1 and the inverter IGBT substrate temperature T2. In this embodiment, the protection limit T1_max is set to 135℃, and the protection limit T2_max is set to 85℃. When T1 or T2 exceeds the limit, an emergency shutdown protection is initiated. The shutdown protection procedure is as follows: immediately close the motor cooling regulating valve and the inverter cooling regulating valve, close the third throttle valve, output a compressor shutdown command, and allow restarting only after the motor winding temperature T1 and the inverter IGBT substrate temperature T2 drop below the safe temperature (e.g., T1 below 90℃ and T2 below 60℃). If the D4 level severe over-temperature shutdown protection is triggered three times consecutively, or if two or more sensors and valves malfunction simultaneously, the controller executes a safe shutdown procedure and will not automatically restart. Manual intervention is required to troubleshoot the fault before restarting.

[0129] like Figures 2-5 As shown, this invention uses a 500kW unit with an outlet water temperature of 85℃ as an example to illustrate the collaborative control process.

[0130] Operating conditions are as follows: Unit model: 500kW heating capacity centrifugal high-temperature heat pump; refrigerant: R245fa; charge: approximately 280 kg; outlet water temperature: 85℃; return water temperature: 75℃; condensing temperature: Tc = 98℃ (P1 = 1020 kPa); evaporating temperature: Te = 40℃ (P2 = 250 kPa); flash economizer intermediate pressure: approximately 500 kPa (corresponding to saturation temperature of approximately 68℃); compressor motor: 2-pole permanent magnet synchronous motor; rated frequency: 350 Hz; current operating frequency: F = 320 Hz (speed: 19200 r / min); input power: W = 140 kW; ambient temperature: 38℃.

[0131] S1: Parameter acquisition (k=1th cycle)

[0132] Ts = 20 seconds. Data collection results: T1 = 118 ℃, T2 = 72 ℃, T3 = 52 ℃ (the system has just started auxiliary cooling, T3 is still relatively high), P1 = 1020 kPa, P2 = 250 kPa, SH = 7 ℃, Le = 42%, F = 320 Hz, W = 140kW.

[0133] S2: Data Filtering

[0134] alpha = 0.85. First cycle filter initialization: X_f(1) = X_raw(1) (direct assignment during initial sampling). Sensor verification: All channel data are within a reasonable range, with no abnormal markers.

[0135] Status identification: F = 320 Hz >= 300 Hz and W = 140 kW >= 110 kW, determined to be a high load condition.

[0136] S3: Heat Risk Index

[0137] dT1 / dt: No historical data for the first period, so set to 0. dT2 / dt = 0.

[0138] Rm = 0.7*(118-95) / (135-95) + 0.3*0 / 0.5 = 0.7*0.575 + 0 = 0.403.

[0139] Ri = 0.7*(72-60) / (85-60) + 0.3*0 / 0.8 = 0.7*0.48 + 0 = 0.336.

[0140] S4: Target Cooling Capacity

[0141] Qm_loss = 0.045*140 = 6.3 kW.

[0142] Qi_loss = 0.025*140 = 3.5 kW.

[0143] Qm = 6.3*(1+1.5*0.403) = 6.3*1.605 = 10.11 kW. Qi = 3.5*(1+1.5*0.336)= 3.5*1.504 = 5.26 kW.

[0144] Qc = 10.11 + 5.26 = 15.37 kW.

[0145] S5: Cooling Capacity Calculation

[0146] Currently, u3 = 50%, Tc_in(50) = 22 + 0.18 * 50 = 31 ℃.

[0147] Set the target T3 to 38 ℃ (current T3 = 52 ℃ and is still decreasing).

[0148] Calculate the current time Qhex: Th_in = 90 ℃,

[0149] Th_out = T3 = 52 ℃

[0150] Tc_in = 31 ℃, Tc_out approximately 33 ℃ (slightly overheated outlet on the cold side).

[0151] dT1_hex = 90-33 = 57 ℃

[0152] dT2_hex = 52-31 = 21 ℃. LMTD = (57-21) / ln(57 / 21) = 36 / 1.0 = 36 ℃. Qhex = 1.2*36 = 43.2 kW >> Qc = 15.37 kW.

[0153] The cooling capacity is sufficient; u3 = 50% already meets the requirements.

[0154] S6: Refrigerant Distribution

[0155] λ_m = 0.403 / (0.403+0.336) = 0.545.

[0156] λ_i = 0.336 / 0.739 = 0.455.

[0157] Maux = Qc / delta_h_cool = 15.37 / 54.4 = 0.283 kg / s.

[0158] Mm = 0.545*0.283 = 0.154 kg / s. Mi = 0.455*0.283 = 0.129 kg / s.

[0159] From the valve's Cv curve, we find that um = 54% and ui = 45%.

[0160] S7: Main loop constraint determination

[0161] C1: SH = 7 ℃ < 10 ℃. C2: Le = 42% > 25%. C3: P2 = 250 kPa > 200 kPa. C4: eta = 0.283 / 3.2 = 0.088 < 0.10. All four conditions are met; execution is permitted.

[0162] S8: Coordinated Regulation

[0163] Output u3 = 50%. Wait for 3 cycles (60 seconds). In the k=4th cycle, T3 has dropped from 52 ℃ to 41 ℃ (a drop of 11 ℃, satisfying the condition >2 ℃). The cold source is confirmed to be established; output um = 54%, ui = 45%.

[0164] S9: Feedback Correction (K=5th period)

[0165] T1 measured = 114 ℃, T1_pred = 118 + 20*(6.3-10.11) / 12 = 118-6.35 = 111.65℃. e_m = 114-111.65 = +2.35 ℃ < 3 ℃, no correction triggered. T2 measured = 69 ℃, T2_pred = 72+20*(3.5-5.26) / 3.5 = 72-10.06 = 61.94 ℃. e_i = 69-61.94 = +7.06 ℃ > 3 ℃ (large deviation), marked as the first time, not yet meeting the condition of three consecutive cycles, continue monitoring.

[0166] S10: Fault Diagnosis

[0167] D1: T3 = 41 ℃ < T1 = 114 ℃; T3 = 41 ℃ < Th_in = 90 ℃; T2 = 69 ℃ > T_ambient = 38 ℃; P1 = 1020 > P2 = 250. The sensors are consistent.

[0168] D2: After u3 outputs in cycle k=1, T3 decreases as expected, which is normal. um / ui has just been output; observe in the next cycle.

[0169] D3: u3=50% is far from 95%, and T3=41 ℃ is close to the target, so there is no insufficient heat exchange.

[0170] D4: T1=114 < 135, T2=69 < 85, no overheating. All normal.

[0171] S11: Loop

[0172] If there are no shutdown conditions, return to S1 and continue to the k=6th cycle.

[0173] During steady-state operation, some valves on the hot water side user end were suddenly closed, causing the hot water flow rate of the condenser to drop by 50%, and the condensing temperature Tc to rise from 98 ℃ to 108 ℃ within minutes (P1 to rise from 1020 kPa to 1200 kPa), and the compressor input power W to rise from 140 kW to 155 kW.

[0174] Controller (12) response process:

[0175] S3: T1 rises rapidly, dT1 / dt rises to 0.4 ℃ / s, and Rm rises rapidly from 0.4 to above 0.9.

[0176] S4: Qc demand rises to over 22 kW.

[0177] S6: Maux demand rises to 0.40 kg / s.

[0178] S7 constraint determination: eta = 0.40 / 3.2 = 0.125 > eta_max = 0.10. C4 is not satisfied.

[0179] The controller limits Max to no more than 0.32 kg / s (eta=0.10) while reducing um / ui by 20%.

[0180] If the constraint is not met for more than 60 seconds, output the compressor frequency reduction command: F_target = 320*0.85 = 272Hz.

[0181] After frequency reduction, W drops to approximately 105 kW, the heat dissipation load decreases, the Qc demand drops to 14 kW, Maux drops to 0.26 kg / s, and eta = 0.081 < 0.10. The constraint is satisfied again.

[0182] After frequency reduction, T1 dropped from its peak temperature of 128°C to 105°C within approximately 3 minutes, and T2 dropped from 78°C to 63°C. The system then returned to normal control.

[0183] In degraded operation due to sensor failure, assuming that the motor temperature sensor has an open circuit fault during operation, the T1 reading jumps to 200 ℃ (out of the physical reasonable range).

[0184] S2 verification: The single-cycle jump changes from 115 ℃ to 200 ℃, and the jump value is 85 ℃ > 10 ℃ limit, marking the T1 sensor as abnormal.

[0185] S10 D1 Diagnosis: T1 anomaly confirmed. Enter sensor degradation mode.

[0186] The controller uses the estimated value of T1: T1_est = 95 + 0.045*140 / 12*t_run_minutes, where t_run_minutes is the running time.

[0187] Assuming it has been running for 60 minutes, T1_est = 95 + 0.045 * 140 / (12 * 60) = 95 + 0.525 * 60 / 60 ℃ ≈ 95 + 31.5 = approximately 126 ℃ (this is the theoretical value without cooling. Since auxiliary cooling is already running, the actual value should be lower than this value, so a correction factor of 0.6 is used).

[0188] T1_est_corrected ≈ 95+31.5*0.6 = 114 ℃.

[0189] um is limited to no more than 50%, and ui is kept under normal adjustment.

[0190] The output sensor malfunction alarm prompts maintenance personnel to replace the motor temperature sensor.

[0191] The system continues to run, but the heat dissipation margin has decreased, and it awaits maintenance.

[0192] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-temperature heat pump unit electronically controlled cooling system, characterized in that, The system includes a main circulation loop and an auxiliary cooling branch for electronically controlled cooling. The main circulation loop includes an evaporator, a centrifugal compressor, a condenser, a first throttle valve, a flash economizer, and a second throttle valve connected in sequence. The outlet of the second throttle valve is connected to the evaporator. The auxiliary cooling branch includes a heat exchanger. The hot-side inlet of the heat exchanger is connected to the outlet of the condenser, and the cold-side inlet of the heat exchanger is connected to the outlet of the flash economizer. The cold-side outlet of the heat exchanger directly returns to the low-pressure side of the main circulation loop. The coolant at the hot-side outlet of the heat exchanger is electronically cooled and then returns to the low-pressure side of the main circulation loop. The low-pressure side of the main circulation loop is the pipeline between the evaporator outlet and the centrifugal compressor suction port. A third throttling valve is installed at the cold side inlet of the heat exchanger. The refrigerant drawn from the flash economizer is throttled to 180-250 kPa by the third throttling valve before entering the heat exchanger. The electronically controlled heat dissipation system is also equipped with a controller for system operation control, and the controller is connected to the sensors and valves of the electronically controlled heat dissipation system via electrical signals.

2. A collaborative control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 1, characterized in that, Including the following steps: S01. Collect the operating parameters of the high-temperature heat pump unit's electronic control heat dissipation system according to a fixed sampling period Ts. The operating parameters include the motor winding temperature T1, the inverter IGBT substrate temperature T2, the heat exchanger hot side outlet temperature T3, the condensing pressure P1, the evaporating pressure P2, the evaporator outlet superheat SH, the flash economizer liquid level Le, the centrifugal compressor operating frequency F, and the centrifugal compressor input power W. S02. Calculate the motor thermal risk index Rm and the inverter thermal risk index Ri based on the operating parameters; Rm = w1 * (T1 - T1_set) / (T1_max - T1_set) + w2 * (dT1 / dt) / RT1_ref; Ri = w1 * (T2 - T2_set) / (T2_max - T2_set) + w2 * (dT2 / dt) / RT2_ref; Where: T1_set is the target value for motor temperature control; T1_max is the upper limit for motor temperature protection; T2_set is the target value for inverter temperature control; T2_max is the upper limit for inverter temperature protection; w1 is the temperature deviation weight; w2 is the temperature rise rate weight, w1 + w2 = 1; dT1 / dt is the motor temperature change rate, in °C / s, calculated by the difference between two adjacent cycles: dT1 / dt = (T1(k) - T1(k-1)) / Ts; dT2 / dt is the inverter temperature change rate, in °C / s, dT2 / dt = (T2(k) – T2(k-1)) / Ts, k represents the current cycle number, RT1_ref is the reference value for motor temperature rise rate, and RT2_ref is the reference value for inverter temperature rise rate. S03. Predict the heat dissipation load of the motor and the heat dissipation load of the frequency converter based on the compressor input power W, and correct the corresponding heat load based on the heat risk index by setting a correction coefficient. S04. Calculate the refrigerant distribution requirement at the hot side outlet of the heat exchanger based on the heat exchanger's heat exchange capacity and the corrected heat dissipation load of the motor and the frequency converter, and cool the motor and the frequency converter.

3. The coordinated control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 2, characterized in that, In step S03, the predicted motor heat dissipation load Qm_loss = km × W, and the predicted inverter heat dissipation load Qi_loss = ki × W, where km is the motor heat loss ratio coefficient and ki is the inverter heat loss ratio coefficient.

4. The coordinated control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 3, characterized in that, The corrected motor heat dissipation load based on the thermal risk index is Qm = Qm_loss × (1 + Km_risk × Rm), and the corrected inverter heat dissipation load is Qi = Qi_loss × (1 + Ki_risk × Ri), where Km_risk is the motor risk amplification factor with a value of 1.5, and Ki_risk is the inverter risk amplification factor with a value of 1.

5.

5. The coordinated control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 4, characterized in that, In step S04, based on the corrected motor heat dissipation load and inverter heat dissipation load, the opening degree of the third throttle valve is adjusted to control the outlet temperature of the heat exchanger hot side coolant, and the coolant at the outlet of the heat exchanger hot side is distributed. The proportion of refrigerant flow entering the motor cooling branch is λ_m = Qm / (Qm + Qi), and the proportion of refrigerant flow entering the inverter cooling branch is λ_i = Qi / (Qm + Qi).

6. The coordinated control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 5, characterized in that, When the auxiliary cooling branch performs electronically controlled cooling and heat dissipation, the main circulation loop protection constraints are set as follows: SH≤SH_max, where SH_max is the maximum limit value of superheat at the evaporator outlet; Le≥Le_min, where Le_min is the minimum liquid level of the flash economizer; P2≥P2_min, where P2_min is the minimum evaporation pressure of the evaporator; eta≤eta_max, where eta is the flow rate ratio of the auxiliary cooling branch, and eta_max is the maximum flow rate ratio of the auxiliary branch. When the main circulation loop protection constraints are met, the third throttle valve opens according to the flow rate requirement of the auxiliary cooling branch. If any protection constraint is not met, the opening degree of the third throttle valve is limited to increase and then reduced by 20% according to the current opening degree ratio. If the protection constraints are not met for more than 60 seconds, a compressor frequency reduction command is output, where the compressor target frequency F_target = F_current * 0.85, where F_current is the current compressor frequency.

7. The coordinated control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 5, characterized in that, When adjusting the opening of the third throttle valve and the distribution of coolant at the hot side outlet of the heat exchanger, a time-sequenced output strategy is adopted: first, the third throttle valve is opened to the target opening, and based on the steady-state evaporation time established on the cold side of the heat exchanger, the change of the heat exchanger outlet temperature T3 during this time is detected. If T3 is stable within the target range, the regulating valves controlling the flow of the heat exchanger's hot side outlet into the motor cooling branch and the inverter cooling branch are adjusted to the target opening accordingly; if T3 is not stable within the target range, valve abnormalities or heat exchanger abnormalities are identified based on the changes in T3.

8. The coordinated control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 5, characterized in that, Within each sampling period Ts, the heat load is corrected and adjusted based on the measured values ​​of the motor winding temperature T1 and the inverter IGBT substrate temperature T2 and the predicted value of cooling. The heat exchanger's heat exchange per unit temperature UA is corrected based on the measured value of the heat exchanger outlet temperature T3 and the predicted value. Motor winding error e_m(k) = T1_actual(k) - T1_pred(k); The temperature error of the IGBT substrate of the frequency converter is e_i(k) = T2_actual(k) - T2_pred(k); The heat exchanger hot-side outlet temperature error e_hex(k) = T3_actual(k) - T3_pred(k); Where, T1_pred(k)=T1(k-1)+Ts*(Qm_loss-Qm_actual) / Cth_motor, Cth_motor is the heat capacity of the motor windings and core; Qm_actual is the actual heat power carried away by the motor cooling branch, in W; Qm_actual=cp_c·ṁ_m·(Tc_out,m−Tc_in,m), where: cp_c is the specific heat capacity of the refrigerant at constant pressure, in J / (kg·℃); ṁ_m is the mass flow rate of the refrigerant in the motor cooling branch, in kg / s; Tc_out,m is the outlet temperature of the refrigerant in the motor cooling branch, in ℃; Tc_in,m is the inlet temperature of the refrigerant in the motor cooling branch, in ℃; T2_pred(k)=T2(k−1)+Ts·(Qi_loss−Qi_actual) / Cth_inv; Where: Qi_actual is the actual heat power carried away by the inverter cooling branch, in W; Qi_actual=cp_c·ṁ_i·(Tc_out,i−Tc_in,i), ṁ_i is the refrigerant mass flow rate of the motor cooling branch, in kg / s; Cth_inv is the heat capacity of the IGBT module and substrate, in J / ℃; Tc_out,i is the refrigerant outlet temperature of the inverter cooling branch, in ℃; Tc_in,i is the refrigerant inlet temperature of the inverter cooling branch; Heat exchanger hot-side outlet temperature prediction: T3_pred(k) = Th_in − Qhex_actual / (cp_h·ṁ_h), where Qhex_actual is the actual heat exchange of the heat exchanger in W, cp_h is the isobaric specific heat capacity of the hot-side fluid in the heat exchanger in J / (kg·℃), ṁ_h is the mass flow rate of the hot-side fluid in the heat exchanger in kg / s, and Th_in is the inlet temperature of the hot-side fluid in the heat exchanger in ℃. Based on the calculated e_m(k), e_i(k), and e_hex(k), Km_risk, Ki_risk, and UA corrections are performed, where UA is the heat exchanger's heat transfer per unit temperature. If |e_m(k)| is greater than 3℃ for 3 consecutive periods: Km_risk = Km_risk + 0.1 * sign(e_m); and the error is recalculated using the adjusted period as the starting period, with the following limit: 0.5 ≤ Km_risk ≤ 3.0; If |e_i(k)| is greater than 3℃ for 3 consecutive periods, Ki_risk = Ki_risk + 0.1*sign(e_i), and the error is recalculated using the adjusted period as the starting period. The limit is: 0.5 ≤ Ki_risk ≤ 3.

0. If |e_hex(k)| is greater than 5 ℃ for 3 consecutive cycles, UA_new = UA_old * (Qhex_actual / Qhex_target), where Qhex_target = cp_h·ṁ_h·(Th_in − T3_target) is the heat exchange required to reach the target outlet temperature; Qhex_actual = cp_h·ṁ_h·(Th_in − T3_actual); when the measured heat exchange is lower than the target heat exchange, this ratio is less than 1, and UA_new decreases accordingly, with a limit range of: 0.6≤ UA_new / UA_rated ≤1.2, where UA_rated is the calibrated heat exchanger heat exchange per unit temperature. When UA drops below 60% of the calibrated value, a heat exchanger blockage alarm is triggered.

9. The coordinated control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 2, characterized in that, The following four levels of fault diagnosis are performed sequentially on the high-temperature heat pump unit during each sampling period: D1: Sensor data consistency diagnosis: The consistency rule is: T3≤T1, T3<Th_in,T2≥T_ambient,P1> P2, where Th_in is the heat exchanger hot-side inlet temperature and T_ambient is the ambient temperature; The fault sensor localization method combines multi-rule cross-voting with trend verification: each sensor participates in multiple consistency rules, the number of rules violated for each sensor is counted, and the sensor with the most violated rules is identified as the source of the anomaly; and the anomaly is confirmed by combining the change rate verification of the sensor's own historical sequence and the trend consistency verification with the associated quantities. If a sensor is identified as abnormal and this condition persists for three consecutive sampling cycles, the corresponding sensor is marked as abnormal, and the sensor enters degradation mode. For T1 anomalies: replace with estimated values, T1_est = T1_base + km·W / Cth_motor·t_run, where t_run is the cumulative running time since this startup, and T1_base is the initial temperature at startup; For the T2 exception: replace it with an estimated value, T2_est = T2_base + ki·W / Cth_inv·t_run; For T3 anomaly: Estimate T3 by referring to the table based on the opening of the third throttle valve and the condensing pressure P1. At the same time, limit the valve opening um of the motor cooling branch and the valve opening ui of the inverter cooling branch to no more than 50%, and output a sensor fault alarm signal. For P1 or P2 anomalies: Replace with compressor frequency F and thermodynamic model estimated value, P1_est = f_high(F, Th_in), P2_est = f_low(F, T_evap), enter pressure sensor degradation mode, limit compressor frequency F to no more than 85% of the current value, and output pressure sensor fault alarm signal; D2: Valve Response Normality Diagnosis: The response judgment rule is as follows: output the valve opening adjustment amount, collect the corresponding temperature change caused by the valve opening adjustment within the sampling period, and mark the corresponding valve abnormality when the temperature does not change, the direction of change is opposite to the expectation, or the change amount is less than γ times the expected amount. γ is the response effectiveness coefficient, which is 0.3~0.

5. After a valve response is marked as abnormal, the valve enters a degraded mode: the opening of the abnormal valve is fixed at the current value and no longer adjusted, the cooling regulation is handled by the other movable valves, the compressor frequency F is limited to no more than 80% of the current value, and a valve fault alarm signal is output. D3: Diagnosis of heat exchanger heat exchange capacity adequacy: When the electronically controlled cooling demand naturally drives the third throttle valve opening u3 to ≥ 95%, the heat exchange capacity is evaluated, and a three-state determination is adopted: u3<95%: The heat exchange capacity is not fully utilized, and it is judged as "not evaluated". The previous valid diagnosis is retained, and the heat exchanger is not assumed to be normal. u3≥95% and T3 meets the standard: the heat exchange capacity is deemed sufficient; If u3≥95% AND T3>T3_target+10℃ and this condition persists for more than 5 consecutive sampling cycles, then the heat exchanger is deemed to have insufficient heat exchange capacity. At this time, maintain maximum cold source supply, u3=100%, correct UA value online, reduce the temperature target of electronic cooling, increase control temperature, limit compressor frequency F to not exceed 90% of the current value, and output heat exchanger maintenance alarm signal; D4: Serious over-temperature diagnosis of motor or inverter. Set the upper limit of motor winding temperature T1 and inverter IGBT substrate temperature T2. When the limit is exceeded, perform emergency shutdown protection. Shutdown protection procedure: immediately close the motor cooling regulating valve and inverter cooling regulating valve, close the third throttle valve, output the compressor shutdown command, and restart after the motor winding temperature T1 and inverter IGBT substrate temperature T2 drop. If the D4 level severe over-temperature shutdown protection is triggered three times consecutively, or if two or more sensors and valves malfunction simultaneously, the safety shutdown procedure will be executed without restarting.

10. The coordinated control method for the electronically controlled heat dissipation system of a high-temperature heat pump unit according to claim 2, characterized in that, The controller solves the following objective function in each cycle to determine the optimal values ​​of u3, um, and ui: minJ=w_T*[(T1-T1_set) / (T1_max-T1_set)]^2+[(T2-T2_set) / (T2_max-T2_set)]^2+w_E*(Maux / Mmain)^2+w _S*[max(0,SH-SH_max) / SH_max]^2+w_L*[max(0,Le_min-Le) / Le_min]^2+w_P*[max(0,P2_min-P2) / P2_min]^2 Constraints: 0 ≤ u3 ≤ 100%, 0 ≤ um ≤ 100%, 0 ≤ ui ≤ 100%; Maux / Mmain≤eta_max; Weighting coefficients: w_T = 1.0; w_E = 0.4; w_S=8.0; w_L=8.0; w_P=8.0.

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